Problem: 1991 525i running hot.

[pauloko]

Hello.

I am new to this site and I would like to ask a question to the regulars.

This morning I noticed my 1991 BMW 525i running with the tempurature guage at 3/4 to red. I took it for a test drive at lunchbreak: as it heats up from cold it gradually heats up straight past middle and goes directly to 3/4. At this point, it levels out and stops heating up, but as I increase the RPMs I notice the needle creeps past 3/4 and gets closer to red. I've already gave most of my money to my mechanic for other suspension-related problems and I just can't afford to get any more problems looked at. I'd like to try and fix this one myself.

I am not that advanced when it comes to car problems and I would greatly appreciate any advise I could get from the people on this forum. Some people have told me that the problem might be either air in the coolant system or the thermostat needs to be replaced. Does this seem right? What do I need to do next?

Thanks a lot.

- Paul

[Max]

Hi!
I had similar problems with my 92 525. It got worse as time went on and the mecanics at my garage could not find anything wrong. They suspected the water pump but it seemed to work fine.

Problems got worse and finally it started boiling a few times. Then the guys took the water pump down and found the problem. It has plastic shovels and one of them had broken off and the loose part sometimes blocked the rotation - eventually to a total stop.

I suggest you check this. Waiting to long costed me a busted radiator. Expensive!!

Good luck
Max

[AllanS]

Same thing happened to me, but it was the thermostat, stuck closed. It kept coolant from circulating, similar to what happened with Max' water pump. That's the easiest part to get to, and cheapest to replace, so I would check that out first.

[Mr. BILL]

My experience has been that if it's air in the system, it'll cool back down after you start moving. You probably have a bad T-stat, or possibly the water pump. The T-stat is pretty easy and cheap, so it's a good place to start

Email me and I'll shoot you the proceedure.

[pauloko]

Thanks for your responses. My water pump was replaced two years ago, so I'll replace the thermostat first and if that doesn't fix the problem, I'll try and take the water pump down to see if there is any blockage.

Driving home yesterday the temperature was about normal, but this morning it was acting very erraticly, moving up and down throughout the drive. It seems like there could be an obstruction, but the T-stat might as well be changed anyway since it's been a while.

Thanks again for all the info.

[Rodericb]

I'm planning on replacing the radiator ($179 with free shipping on eBay) and water pump ($40) as I've already replaced the thermostat. I've heard that the radiators on 89-92 525i were crappy at best and tend to need replacing if they ever overheat. I've also heard of the problem with the water pump and the plastic impellar (sp) blades. I tend to believe that my problem may be a clogged radiator due to the fact that I cannot see any water flow when the engine is idling and the water hoses on top get hot to the touch.

Hello.

I am new to this site and I would like to ask a question to the regulars.

This morning I noticed my 1991 BMW 525i running with the tempurature guage at 3/4 to red. I took it for a test drive at lunchbreak: as it heats up from cold it gradually heats up straight past middle and goes directly to 3/4. At this point, it levels out and stops heating up, but as I increase the RPMs I notice the needle creeps past 3/4 and gets closer to red. I've already gave most of my money to my mechanic for other suspension-related problems and I just can't afford to get any more problems looked at. I'd like to try and fix this one myself.

I am not that advanced when it comes to car problems and I would greatly appreciate any advise I could get from the people on this forum. Some people have told me that the problem might be either air in the coolant system or the thermostat needs to be replaced. Does this seem right? What do I need to do next?

Thanks a lot.

- Paul