Hello this is going to be a long read but I have been slowly trying to restore my 1984 bmw 533i 5 speed bronzit beige…
In the process of keeping maintenance up to date I had to refresh the whole cooling system before I continue car has never overheated prior to the cooling system refresh and ran good.
So I ended up replacing
Radiator
All hoses and clamps
Every bolts, nuts, clips
Thermostat
T shape piece
Water pump
Fan clutch
Thermostat housing and gaskets
New gasket for rear cover of the head
Serpentine belt
All sensors
Cap
Coolant sensor
Coolant reservoir
I went almost all way out to prevent any coolant leaks and preventing from overheating from worn out parts
The last step was to bleed the system which I believe I did successfully. But the issue is ever since the refresh car overheats like 10-30 mins of idling and the weird part is my e28 only overheats when hood is closed and heater is off.
I filled the the coolant to the line let it idle with the hood up for 30mins to a hour and it doesn’t over heat front of the engine feels super hot and the moment I closed the hood 10 mins later needle starts creeping past halfway mark I get out and open the hood and the coolant has expanded from the line all the way to the top of the reservoir
I have changed the water pump 3x same as thermostats 3x rechecked the thermostat to be installed correctly but I’m stumped and can’t figure out why this darn car keeps overheating
Did a combustion chem test color changed to light blue
Car doesn’t throw white smoke at all
No liquid mixing on either coolant or oil
So I think bad head gasket can be ruled out ?
Any advise would be appreciated thank you for reading
84 bmw 533i really strange overheating
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Charliecharlie
- Posts: 16
- Joined: May 29, 2019 10:16 PM
- Location: Washington
Re: 84 bmw 533i really strange overheating
This is probably going to be a bit of a ramble, but it should apply.
Bleeding the system. My experience has always been if the heater works the system is bled.
It doesn't sound like a blown HG, but don't discount a cracked head. Running, but of course don't open the cap hot, but running, look into the coolant reservoir. You should not see bubbles. It can be hard to tell the difference, but turbulence yes, bubbles no, that's often a cracked head, but the combustion chamber test should have shown that.
There is an early and a late thermostat, I think the change was 86 or 87. Make sure you've got the right on in there. And see if you can find the casting date on the housing, it's possible a different one has been put in over the past 40 years.
After it's warmed up, shut it off and feel the radiator. It should feel hot. Everywhere vertically, meaning you have flow. Hit it with an infared temp gun if you have one to see where its hot and if it's cold in places. As cheap as they are it might be worth investing in. If the cold side of the rad is cold, it suggests a flow problem. If it's hot, that's more troubling.
Test the fan clutch. Warm it up, get it good and warm or even hot. Stick a newspaper in there. Gently. You should not be able to stop the fan with the newspaper. Yes I know, a newspaper, but find one, it's a good test. This test has to be warm to hot.
Bleeding the system. My experience has always been if the heater works the system is bled.
It doesn't sound like a blown HG, but don't discount a cracked head. Running, but of course don't open the cap hot, but running, look into the coolant reservoir. You should not see bubbles. It can be hard to tell the difference, but turbulence yes, bubbles no, that's often a cracked head, but the combustion chamber test should have shown that.
There is an early and a late thermostat, I think the change was 86 or 87. Make sure you've got the right on in there. And see if you can find the casting date on the housing, it's possible a different one has been put in over the past 40 years.
After it's warmed up, shut it off and feel the radiator. It should feel hot. Everywhere vertically, meaning you have flow. Hit it with an infared temp gun if you have one to see where its hot and if it's cold in places. As cheap as they are it might be worth investing in. If the cold side of the rad is cold, it suggests a flow problem. If it's hot, that's more troubling.
Test the fan clutch. Warm it up, get it good and warm or even hot. Stick a newspaper in there. Gently. You should not be able to stop the fan with the newspaper. Yes I know, a newspaper, but find one, it's a good test. This test has to be warm to hot.
Re: 84 bmw 533i really strange overheating
In the spirit of clarity, I want to ask some questions. Forgive me if these appear obvious and I'm sure you've addressed most (if not all) of them but in reading and re-reading your post, you didn't mention a few thing. Note, I'm not saying you don't have an issue, it certainly appears something is amiss, we just need to understand how severe it is.
1. "Overheating": When you say it is overheating, what exactly do you mean? You say you witness the temp gauge rising past the half-way mark after 30 minutes of idling (only with the hood closed), but does it continue to rise beyond that or does it stop there? You don't say. Likewise, when the hood is open, where does the temp gauge stop? Research the normal operating temps for the M30Bxx motors, this link has some good info if you've not found it already: https://www.mye28.com/tech/rods_pages/id9.html
2. Temperature gauges and the whole cluster can go bad as the SI board attached to them suffer and/or fail (usually from leaking batteries). It could be possible the gauge is inaccurate as this ailment is more common than not especially after 35+ years. Before you did this cooling system overhaul, what was the cars and this gauges behavior? Anything erratic happen, anything like this before?
3. I imagine that in the whole overhaul, you would have drained all the coolant at least once. Did you actually do a block drain or flush (i.e. fill, open up the block drain plug, drain, close, refill, and repeat again)? Provided you did the bleeding correctly, it is unlikely there will be any trapped air left in the system but you never know (with such a rapid temp rise, it sounds like it to me). Other possibility, although a long shot, is there a blockage in the cooling ports (either by corrosion or sediments from poor maintenance, etc.). Do you know the prior maintenance of this motor? How well was it taken care of? Did they use correct coolant and changed it every 2 years?
4. Radiator: Make sure you have the correct radiator (I know it sounds obvious). There is much debate about which brand is better these days, but I had erratic or higher than (my) normal engine temps after I replaced my South African Behr radiator about 4-5 years ago. Somewhere along the line, Behr changed the internal design of the cooling tubes making them markedly less efficient than the previous design (however, this did not apply to the BMW branded Behr units, only the OEM retail versions). Nissens is still based on the older design (I can't recall the specifics but has to do with either flat tubes or round tubes) which makes it a better performing unit. I went through 3 SA Behrs in that exercise (2 leaked out of the box) and after a summer of getting ulcers watching my temp gauge move higher each time, I switched out to a Nissens and the engine temps have been rock solid at 3/8's ever since.
5. Head Bolts: Check to torque specs on the cylinder head bolts. This sounds odd and again a long shot, but it's worth the simple exercise. Read up on the torque procedure, but there is wild outside chance that one or two or many have lost their final torque spec. This could lead to a loss of coolant and higher than normal temperatures. This happened to me when a few of mine weren't at the full final last torque and coolant was escaping the system as it was leaking into the cylinders and blown out the exhaust in tiny amounts. However it more likely it is either a bad head gasket or cracked head (or block) as Mike mentioned; but this is a simple procedure to perform for peace of mind.
My bets are on some kind of blockage somewhere which is preventing proper coolant circulation but unfortunately can't provide any more information on finding it and solving it if there is. Either that or it's as simple as a non-functioning fan clutch.
Good luck and keep us posted.
1. "Overheating": When you say it is overheating, what exactly do you mean? You say you witness the temp gauge rising past the half-way mark after 30 minutes of idling (only with the hood closed), but does it continue to rise beyond that or does it stop there? You don't say. Likewise, when the hood is open, where does the temp gauge stop? Research the normal operating temps for the M30Bxx motors, this link has some good info if you've not found it already: https://www.mye28.com/tech/rods_pages/id9.html
2. Temperature gauges and the whole cluster can go bad as the SI board attached to them suffer and/or fail (usually from leaking batteries). It could be possible the gauge is inaccurate as this ailment is more common than not especially after 35+ years. Before you did this cooling system overhaul, what was the cars and this gauges behavior? Anything erratic happen, anything like this before?
3. I imagine that in the whole overhaul, you would have drained all the coolant at least once. Did you actually do a block drain or flush (i.e. fill, open up the block drain plug, drain, close, refill, and repeat again)? Provided you did the bleeding correctly, it is unlikely there will be any trapped air left in the system but you never know (with such a rapid temp rise, it sounds like it to me). Other possibility, although a long shot, is there a blockage in the cooling ports (either by corrosion or sediments from poor maintenance, etc.). Do you know the prior maintenance of this motor? How well was it taken care of? Did they use correct coolant and changed it every 2 years?
4. Radiator: Make sure you have the correct radiator (I know it sounds obvious). There is much debate about which brand is better these days, but I had erratic or higher than (my) normal engine temps after I replaced my South African Behr radiator about 4-5 years ago. Somewhere along the line, Behr changed the internal design of the cooling tubes making them markedly less efficient than the previous design (however, this did not apply to the BMW branded Behr units, only the OEM retail versions). Nissens is still based on the older design (I can't recall the specifics but has to do with either flat tubes or round tubes) which makes it a better performing unit. I went through 3 SA Behrs in that exercise (2 leaked out of the box) and after a summer of getting ulcers watching my temp gauge move higher each time, I switched out to a Nissens and the engine temps have been rock solid at 3/8's ever since.
5. Head Bolts: Check to torque specs on the cylinder head bolts. This sounds odd and again a long shot, but it's worth the simple exercise. Read up on the torque procedure, but there is wild outside chance that one or two or many have lost their final torque spec. This could lead to a loss of coolant and higher than normal temperatures. This happened to me when a few of mine weren't at the full final last torque and coolant was escaping the system as it was leaking into the cylinders and blown out the exhaust in tiny amounts. However it more likely it is either a bad head gasket or cracked head (or block) as Mike mentioned; but this is a simple procedure to perform for peace of mind.
My bets are on some kind of blockage somewhere which is preventing proper coolant circulation but unfortunately can't provide any more information on finding it and solving it if there is. Either that or it's as simple as a non-functioning fan clutch.
Good luck and keep us posted.
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Charliecharlie
- Posts: 16
- Joined: May 29, 2019 10:16 PM
- Location: Washington
Re: 84 bmw 533i really strange overheating
Thanks Mike I have tested the fan clutch when car is up to temp and it seems good no slowing or stopping at all.
I’m still a bit suspicious about the thermostat I have changed it three times 1 from pelican and the other two from local auto parts store no change. my heater works but the only issues is with the heat controls I can’t open my vents the slides move but I think previous owner disconnected from the wires that open and close the vents I’m not sure if that can be a issue. But with the heater on
I can see the coolant in the reservoir go down a bit. I will check for bubbles today I’ll add a update.
I checked the radiator yesterday by touch when car is hot i don’t have an infrared to check hot and cold and every side of the radiator seems hot .
I’m still a bit suspicious about the thermostat I have changed it three times 1 from pelican and the other two from local auto parts store no change. my heater works but the only issues is with the heat controls I can’t open my vents the slides move but I think previous owner disconnected from the wires that open and close the vents I’m not sure if that can be a issue. But with the heater on
I can see the coolant in the reservoir go down a bit. I will check for bubbles today I’ll add a update.
I checked the radiator yesterday by touch when car is hot i don’t have an infrared to check hot and cold and every side of the radiator seems hot .
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Charliecharlie
- Posts: 16
- Joined: May 29, 2019 10:16 PM
- Location: Washington
Re: 84 bmw 533i really strange overheating
Thanks vin and I imagined I left a lot of details out but here it goes
1. So when I start the car let it idle the needle eventually reaches the middle with the hood open the needle doesn’t move it stays solid in the middle when I turn on the heater the needle goes down a bit and stays like that till I shut off the heater or the car l. Well when the car is idling l, needle in the middle and I go out close the hood get back inside the car and watch the temp the needle slowly starts moving to 3/4 of the temp gauge.
And to be honest I haven’t let it passed more than that because I’m scared of blowing the gasket or damaging the head I shut it off open the hood it’s really hot even the handle is hot and either the coolant has risen almost to the very top of the reservoir or it’s bubbling pouring out from the escape hose.
2. I’ve done a lot of work on this car and I have replaced the si board with new updated ones that don’t require the batteries I know the cluster has issues with si batteries going out or leaking and being a finicky cluster so I ordered the updated ones from FCP euro just to have a working temp and gas gauge.
3. Yes drained and refilled 3 or 4 time to get out the old coolant which used to be green and put new bmw blue coolant in there. Raised the engine where the bleeder screw is the highest point, heat on full blast and pour and bleed also removed the hose that goes from the radiator to the reservoir raised the hose high and filled the reservoir till water started pouring from the hose and then put hose back in place. No maintenance records when car was bought. I do think there can be a blockage because yesterday doing some trouble shooting I ended up draining the little coolant it had from the radiator and block started to refill open the bleeder screw and nothing would come out from the bleeder screw and the upper radiator hose feels really soft when I squeeze it like I can’t feel any movement of water and also coolant reservoir was full and wouldn’t go down not even by squeezing the hoses the water wouldn’t flow thru the cooling system only way was to suck the hose slowly from reservoir side end that connects to radiator with bleeder screw closed and cap on that’s the only way the coolant started moving thru out the system so I am thinking it could be a blockage somewhere.
4. Radiator is a year old and it was bought from FCP euro nissen brand yesterday checked for any blockage in it water flows good thru it also no gunk came out of it.
5. This I haven’t checked I have searched e28 forums a lot and I have came across couple posts about people mentioning lose head bolts I will have to try this out once I’m off work today
Thank you vin will definitely do keep updating on this situation
1. So when I start the car let it idle the needle eventually reaches the middle with the hood open the needle doesn’t move it stays solid in the middle when I turn on the heater the needle goes down a bit and stays like that till I shut off the heater or the car l. Well when the car is idling l, needle in the middle and I go out close the hood get back inside the car and watch the temp the needle slowly starts moving to 3/4 of the temp gauge.
And to be honest I haven’t let it passed more than that because I’m scared of blowing the gasket or damaging the head I shut it off open the hood it’s really hot even the handle is hot and either the coolant has risen almost to the very top of the reservoir or it’s bubbling pouring out from the escape hose.
2. I’ve done a lot of work on this car and I have replaced the si board with new updated ones that don’t require the batteries I know the cluster has issues with si batteries going out or leaking and being a finicky cluster so I ordered the updated ones from FCP euro just to have a working temp and gas gauge.
3. Yes drained and refilled 3 or 4 time to get out the old coolant which used to be green and put new bmw blue coolant in there. Raised the engine where the bleeder screw is the highest point, heat on full blast and pour and bleed also removed the hose that goes from the radiator to the reservoir raised the hose high and filled the reservoir till water started pouring from the hose and then put hose back in place. No maintenance records when car was bought. I do think there can be a blockage because yesterday doing some trouble shooting I ended up draining the little coolant it had from the radiator and block started to refill open the bleeder screw and nothing would come out from the bleeder screw and the upper radiator hose feels really soft when I squeeze it like I can’t feel any movement of water and also coolant reservoir was full and wouldn’t go down not even by squeezing the hoses the water wouldn’t flow thru the cooling system only way was to suck the hose slowly from reservoir side end that connects to radiator with bleeder screw closed and cap on that’s the only way the coolant started moving thru out the system so I am thinking it could be a blockage somewhere.
4. Radiator is a year old and it was bought from FCP euro nissen brand yesterday checked for any blockage in it water flows good thru it also no gunk came out of it.
5. This I haven’t checked I have searched e28 forums a lot and I have came across couple posts about people mentioning lose head bolts I will have to try this out once I’m off work today
Thank you vin will definitely do keep updating on this situation
Re: 84 bmw 533i really strange overheating
Hood open is ok but hot when closed....Are you sure about the right fan clutch/fan position????....sound to me like they are inverted, hood open there is a lot of fresh air but there is not enought when closed, specially if the car is not moving
Re: 84 bmw 533i really strange overheating
Just thought of something else, what kind of radiator? While I haven't seen anything as dramatic as you seem to have going on, there have been a lot of reports of problems with the South African radiators, the ones with the round tubes. Do you have round or flat radiator tubes?
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Charliecharlie
- Posts: 16
- Joined: May 29, 2019 10:16 PM
- Location: Washington
Re: 84 bmw 533i really strange overheating
So the fan clutch is a meyle i wanted to go with sach since it’s a brand i normally use for all my bimmers but meyle had good reviews and wasn’t quite expensive as sach at the time
My radiator is a nissen one and are flats
My radiator is a nissen one and are flats
Re: 84 bmw 533i really strange overheating
Did you replace any of the sensors on either the radiator and thermostat housing?
Is it possible you have the wrong ones and/or in the wrong positions?
Is it possible you have the wrong ones and/or in the wrong positions?
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Charliecharlie
- Posts: 16
- Joined: May 29, 2019 10:16 PM
- Location: Washington
Re: 84 bmw 533i really strange overheating
Yes I did pretty much all sensors on radiator and thermostat housing except 1 which is think is the temperature time switch
Part number 13621362599 I took pictures before removing so I knew which order they were in
I hope not one of them was pretty hard to find which was the sensor that throws the signal to the temp gauge FCP was back ordered I ended buying a new one from eBay I
Can try to check it out with the multimeter on the resistance/ ohms on the sensors
Part number 13621362599 I took pictures before removing so I knew which order they were in
I hope not one of them was pretty hard to find which was the sensor that throws the signal to the temp gauge FCP was back ordered I ended buying a new one from eBay I
Can try to check it out with the multimeter on the resistance/ ohms on the sensors
Re: 84 bmw 533i really strange overheating
Normally e28 temp gauge is 1/4 or 3/8 when hot but no 1/2 or more as you mention.
Did you check the right position of all the rear hoses, heather hoses I mean, T connector, etc when re assembling??
Is the AC radiator (condenser in front of the water radiator) clean to allow air going thru???
Finally, any chance to re use the old radiator to discard any problem with the new unit???
If the engine worked well before all the new parts replacement there is no reason to overheat with new parts.
Did you check the right position of all the rear hoses, heather hoses I mean, T connector, etc when re assembling??
Is the AC radiator (condenser in front of the water radiator) clean to allow air going thru???
Finally, any chance to re use the old radiator to discard any problem with the new unit???
If the engine worked well before all the new parts replacement there is no reason to overheat with new parts.
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Charliecharlie
- Posts: 16
- Joined: May 29, 2019 10:16 PM
- Location: Washington
Re: 84 bmw 533i really strange overheating
Yes I have double checked all hoses from the rear also looking out for any leaks and I havent found any yet
The aux fan is clean but it doesn't turn on it keeps melting my fuses same as for the heater that another issue I have to address for the car.
I wish I would've kept my old parts but didn't have storage to store them and ended up dumping them stupid of me
The aux fan is clean but it doesn't turn on it keeps melting my fuses same as for the heater that another issue I have to address for the car.
I wish I would've kept my old parts but didn't have storage to store them and ended up dumping them stupid of me
Re: 84 bmw 533i really strange overheating
Maybe you already read this, but important to check what type of thermostat is used:
https://www.mye28.com/viewtopic.php?t=150966
Some similar issues from UK:
http://www.bavarian-board.co.uk/forum_p ... ting-still
Another thermostat (also new) issue:
https://www.bimmerwerkz.com/threads/e28 ... ing.72353/
It's a shame you lost the old parts but I can say that the Nissens radiator is good, I changed my original 30+ year old radiator and the new one works perfectly.
Check that the new fan clutch really engages and again, that the fan is facing the correct way. If it worked well before, something of the new part did not fit properly or is bad (nothing unusual with the new parts they sell today for these cars)....and make sure to do a good air bleeding.
https://www.mye28.com/viewtopic.php?t=150966
Some similar issues from UK:
http://www.bavarian-board.co.uk/forum_p ... ting-still
Another thermostat (also new) issue:
https://www.bimmerwerkz.com/threads/e28 ... ing.72353/
It's a shame you lost the old parts but I can say that the Nissens radiator is good, I changed my original 30+ year old radiator and the new one works perfectly.
Check that the new fan clutch really engages and again, that the fan is facing the correct way. If it worked well before, something of the new part did not fit properly or is bad (nothing unusual with the new parts they sell today for these cars)....and make sure to do a good air bleeding.
Re: 84 bmw 533i really strange overheating
My experience with my 84 525i (with a 3.5 in it) is that the clutch fan at idle doesn't move enough air to keep the temps in the normal range. My car does not have AC and so it did not come with the aux fan. If I gave the car a bit of a rev, maybe held to 1000 rpm the temps dropped right back to where they should be almost instantly.
See if a gentle rev when it is getting hot with the hood down brings the temps back down to where they should be. If it does then getting that Aux fan going should be your first priority and should hopefully take care of your issues.
For my car I am now running a pair of thin SPAL fans controlled by my standalone ECU based off temp and car speed in place of the clutched fan. People talk down about this style of fan as they don't move as much air as a mechanical clutched fan, that is true but it is my belief that the mechanical style moves so much air because it is controlled so poorly that they are trying to make sure it is always moving more than enough air, like I said though I found it wasn't at idle. With my current setup I can pull off track with a fully heat soaked car without a cooldown lap and go right to sitting at idle with temps never moving.
The only other thing I'll add is that my last clutched fan I had replaced the clutch on and it failed within a year but not in a typical way. It had the external bi-metalic strip that acted on a small plunger in the centre to engage the clutch as it got warm (pulled out the plunger from memory). That plunger had disengaged from the clutch so even though it was spinning the fan it was not engaging. When the clutch fan is engaged it should be obvious, as soon as you rev the engine you can hear it moving lots of air and even feel it dragging on the car when accelerating (big reason I went to electric, sucked sitting in line to run at an autocross just to have the fan eat a bunch of power).
Hope you find the solution!
See if a gentle rev when it is getting hot with the hood down brings the temps back down to where they should be. If it does then getting that Aux fan going should be your first priority and should hopefully take care of your issues.
For my car I am now running a pair of thin SPAL fans controlled by my standalone ECU based off temp and car speed in place of the clutched fan. People talk down about this style of fan as they don't move as much air as a mechanical clutched fan, that is true but it is my belief that the mechanical style moves so much air because it is controlled so poorly that they are trying to make sure it is always moving more than enough air, like I said though I found it wasn't at idle. With my current setup I can pull off track with a fully heat soaked car without a cooldown lap and go right to sitting at idle with temps never moving.
The only other thing I'll add is that my last clutched fan I had replaced the clutch on and it failed within a year but not in a typical way. It had the external bi-metalic strip that acted on a small plunger in the centre to engage the clutch as it got warm (pulled out the plunger from memory). That plunger had disengaged from the clutch so even though it was spinning the fan it was not engaging. When the clutch fan is engaged it should be obvious, as soon as you rev the engine you can hear it moving lots of air and even feel it dragging on the car when accelerating (big reason I went to electric, sucked sitting in line to run at an autocross just to have the fan eat a bunch of power).
Hope you find the solution!
Re: 84 bmw 533i really strange overheating
I just noticed you said you replaced the thermostat housing. Is it an early or late and did the stat match it or did you order it for the year of the car? You might have a late housing but an early stat. What that does I don't know, but it might be the issue.
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Charliecharlie
- Posts: 16
- Joined: May 29, 2019 10:16 PM
- Location: Washington
Re: 84 bmw 533i really strange overheating
Hey guys quick update and fix for it
Aldo and Mike are spot on check my housing does have letter a stamp on so I ordered a thermostat for a 88 535i installed it and so far no overheating or coolant bubbling, engine is hot but not as much compared to the previous times I want to thank you all for the help and advice now I only have a issue with with 1k RPM on idle so I will start trouble shooting soon on that thank you all ..
Aldo and Mike are spot on check my housing does have letter a stamp on so I ordered a thermostat for a 88 535i installed it and so far no overheating or coolant bubbling, engine is hot but not as much compared to the previous times I want to thank you all for the help and advice now I only have a issue with with 1k RPM on idle so I will start trouble shooting soon on that thank you all ..