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E28 (1982 - 1988)

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  #1  
Old 03-23-2011, 03:59 PM
Boiwonder Boiwonder is offline
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Mein Auto: E28 535I 1985
85 535i Overheat

I got my black 535i which has a history in heating up in the past year and a half I had it I fixed it this problem a while back but now I'm getting a little worried because today for the first time in 6 months it heated up.

I know it's not the fan, I got it a new fan clutch
Coolants good.
Any other options I should check?
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  #2  
Old 03-23-2011, 05:38 PM
south26 south26 is offline
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Mein Auto: 535i 1989
It could be that the coolant cap has gone bad. Or yo have some air in the system.

Andy
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  #3  
Old 03-23-2011, 09:34 PM
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catso catso is offline
catso
Location: Chicago
 
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Mein Auto: 2000 323i, 1988 528e
Old radiators lose some of their cooling and flow efficiency from corrosion and dirt buildup. The thermostat may not fuction properly. Or you might be able to switch to a lower temp rating. There are also aftermarket sensors that turn on the auxiliary fan at lower temps. Sometimes it's as simple as a loose fan belt, or bleeding the system properly, or a bad cap. Vacuum leaks can cause an engine to run lean. The wrong heat range for you spark plugs can contribute to the problem. Neglecting to change the coolant regularly can lead to problems that clog or restrict the system's flow. What did you have "fixed" that solved your previous problem?
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  #4  
Old 03-24-2011, 09:20 PM
Boiwonder Boiwonder is offline
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Mein Auto: E28 535I 1985
you have a very good point about the radiator being old and does need to be cleaned. how should I clean it? as much as the engine runs smooth alot of times it keeps sputtering and run a little lean so how do I check and fix these minor vacuum leaks which I believe is contributing to the issue. All the belts and hoses have been replaced recently including a new spark plug wire set and distributor cap. I fixed this problem by just replacing the fan clutch which was really old and that fixed the problem immediately and for a long period of time.

Thanks for your input very helpful!
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  #5  
Old 03-24-2011, 09:39 PM
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catso catso is offline
catso
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Quote:
Originally Posted by Boiwonder View Post
you have a very good point about the radiator being old and does need to be cleaned. how should I clean it? as much as the engine runs smooth alot of times it keeps sputtering and run a little lean so how do I check and fix these minor vacuum leaks which I believe is contributing to the issue. All the belts and hoses have been replaced recently including a new spark plug wire set and distributor cap. I fixed this problem by just replacing the fan clutch which was really old and that fixed the problem immediately and for a long period of time.

Thanks for your input very helpful!
You can try using one of the cooling system flush chemicals available, that may work, but replacing the radiator may be the better option. When you say all the hoses, are you including the vacuum hoses and elbows? The intake boots from the air flow meter to the throttle body could be cracked and leaking. I would take all that stuff apart, carefully examine it, clean the IAC valve and passages, clean the throttle body, clean the AFM, and remove a couple of plugs and evaluate their condition. Try to determine whether it's a mixture related problem or cooling system issue. You might need to change your oxygen sensor. Lots of things can contribute. I once had an intermittent problem with a crankshaft position sensor that caused a similar problem.
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  #6  
Old 03-24-2011, 10:07 PM
Boiwonder Boiwonder is offline
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Thanks again for the point! yes including vacuum hoses and elbows. I think you are spot on to my problem because my car is showing symptoms. I will clean the radiator, I will check the intake boots, clean the IAC valve and passages, clean the throttle body and AFM. I will also check the Oxygen sensors and I bet I will find the problem!

Thanks alot!
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  #7  
Old 04-03-2011, 08:48 PM
Boiwonder Boiwonder is offline
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Mein Auto: E28 535I 1985
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Quote:
Originally Posted by catso View Post
You can try using one of the cooling system flush chemicals available, that may work, but replacing the radiator may be the better option. When you say all the hoses, are you including the vacuum hoses and elbows? The intake boots from the air flow meter to the throttle body could be cracked and leaking. I would take all that stuff apart, carefully examine it, clean the IAC valve and passages, clean the throttle body, clean the AFM, and remove a couple of plugs and evaluate their condition. Try to determine whether it's a mixture related problem or cooling system issue. You might need to change your oxygen sensor. Lots of things can contribute. I once had an intermittent problem with a crankshaft position sensor that caused a similar problem.
Hey Catso your advise helps so much.
first i looked at my intake boot guess what it wasn't on right, it was slipping off!! So I adjusted it and put it in tighter
I checked the Idle Control Valve I cleaned it good.
I checked all the vacuum hoses around it is good but i found one it's torn and it leads straight to the intake boot. I looked it up on realoem.com and found this unique peace
it's #11 called a vent hose and then #10 the support. that plastic peace melted.
I cleaned the MAF with MAF Cleaner it was real dirty.

I'm going to order the vent hose and support part soon.
the intake boot is good after i put it on right.

I feel like my car can still run better what else should I do?
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  #8  
Old 04-03-2011, 09:04 PM
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catso catso is offline
catso
Location: Chicago
 
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Quote:
Originally Posted by Boiwonder View Post
Hey Catso your advise helps so much.
first i looked at my intake boot guess what it wasn't on right, it was slipping off!! So I adjusted it and put it in tighter
I checked the Idle Control Valve I cleaned it good.
I checked all the vacuum hoses around it is good but i found one it's torn and it leads straight to the intake boot. I looked it up on realoem.com and found this unique peace
it's #11 called a vent hose and then #10 the support. that plastic peace melted.
I cleaned the MAF with MAF Cleaner it was real dirty.

I'm going to order the vent hose and support part soon.
the intake boot is good after i put it on right.

I feel like my car can still run better what else should I do?
New plugs, adjust the valves (which will require a new valve cover gasket that might also be contributing to your vaccuum leak problem), possibly clean or replace the fuel injectors, you could have a bad fuel pressure regulator, confirm that the temperature sensors are working correctly, etc. A Bentley's manual would help you alot. Keep working on it and I'll come up with some more ideas.
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  #9  
Old 04-03-2011, 09:28 PM
Boiwonder Boiwonder is offline
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Location: Utah
 
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Mein Auto: E28 535I 1985
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Quote:
Originally Posted by catso View Post
New plugs, adjust the valves (which will require a new valve cover gasket that might also be contributing to your vaccuum leak problem), possibly clean or replace the fuel injectors, you could have a bad fuel pressure regulator, confirm that the temperature sensors are working correctly, etc. A Bentley's manual would help you alot. Keep working on it and I'll come up with some more ideas.
I got new spark plugs already but should I get a particular kind I have NGK on em should I get like Bosch?
Adjusting the valves was something I was considering I will be doing that eventually.

I did put injector cleaners in yesterday but replacing them is a big job so i'll also save that for another project later on. I think your right about the fuel pressure regulator where can I find it? or maybe what category will it be in on realoem.com

Last I did order a bentley Manual a few hours ago! haha awesome.

Thanks for your help I will update you more when I get to it!
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  #10  
Old 04-03-2011, 10:23 PM
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catso catso is offline
catso
Location: Chicago
 
Join Date: Dec 2009
Posts: 2,931
Mein Auto: 2000 323i, 1988 528e
Quote:
Originally Posted by Boiwonder View Post
I got new spark plugs already but should I get a particular kind I have NGK on em should I get like Bosch?
Adjusting the valves was something I was considering I will be doing that eventually.

I did put injector cleaners in yesterday but replacing them is a big job so i'll also save that for another project later on. I think your right about the fuel pressure regulator where can I find it? or maybe what category will it be in on realoem.com

Last I did order a bentley Manual a few hours ago! haha awesome.

Thanks for your help I will update you more when I get to it!
The plugs you have should be ok, but you can experiment with other types and heat ranges. Removing and replacing the injectors isn't really as hard as it looks. On my 528e they come out fairly easily if you take off the valve cover first. You can then send your injectors out to be ultrasonically cleaned and tested. The Bosch fuel pressure regulator you might be able to get at Parts Train for $42. Get the part number from RealOEM.com in the fuel preparation category and then search on FrugalMechanic.com.
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