BimmerFest BMW Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
i have no idea what is going on... my car may be haunted.

the problem i have is overheating. my mechanic friends have looked into this for me over the last 2 weeks, and they had found several items that needed replacement, and we also just went ahead and replaced a couple other things so all the engine cooling parts are new...

at first the car (95' 525, 100k) would redline and give me the coolant level warning after driving @ 6 miles or so. we did coolant flush, and it was ok for a couple days. then it happened more and more, we looked at thermostat, and it turned out the housing had a crack and the thermostat was in pieces. we replaced those, yet a few days later it overheated again(we had a stretch of 100degree days at the time also). after much trial and error we found the fan clutch had issues and changed that.

the car has also had a full tune up (2 mo. ago)

the only odd thing i notice is that it seems to be fine when i go 35 mph or less, once i get to higher speeds the thermostat gauge jumps to 3/4 and approaches red if your gunning the motor (ie on the highway) but if u stop at a light or slow down , the gauge goes back to normal. and once i do get to around 35- 40 mph the rpms go up, the engine feels like its crankin away, but the car has nop pick up and sort of feels sluggish.

could this be a transmission problem? the engine feels under great pressure at 35+mph but doesnt seem to actually release it as actual speed/motion like you expect. unfortunately this transm. is not the original, 2 yrs ago i got the trans control message and had the same sort of stuck in 3rd thing going on, and my then "professional" mechanic said i needed to replace the thing. since the car had a ton of issues back then and wasnt worth the $ to fix it all, i went cheap and he put in a gm transm. but since i recently found this website and have a mechanic that charges me for parts only(!) weve corrected everything in 2 months for @$800 that the "pro" mechanics could never fix for the last 5 years and would have easily charged me well @ $5000. all thats left is this freaky heat problem.

could this be something as simple as a bad gauge? how can you check those?

i also spoke to a girl who had the opposite problem in her ford escape, the gauge would drop to cold, because her gas pedal would stick to the floor! her dealer said the fan was being fooled into thinking she was doing 100 mph or something.

any help would be appreciated
 

·
The Biggest P0st Whore!!
Joined
·
2,912 Posts
The radiator may be clogged or you may be having water pump problems. Did you find all the parts of the broken thermostat? They could be blocking passages some where. The lack of pickup could be maintence related. Check plugs and other tuneup items.

Your lady friends problem shouldnt happen. The thermostat only opens when the temp reaches a certian range. Even if the fan was running full out it shouldnt cause the car to run cold. If it did cars would go cold anytime you were running the AC as this turns the fan on also.

BTW "@ = at"
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #3 ·
thanks for the reply...
my friend was also suspicious of pump and radiator as they are the only suspects left! the pump does not make any odd noises and does not leak as we can see, but how do u know if radiator is clogged? and how do u unclog? the thermostat pieces are all acounted for btw.

does a clog somehow relate to the heating up over 35 mph and cooling down at slower speeds or stopped?


(ps... prior to being popularized by internet usage, in architectural drawing shorthand we used "@" for "about" &/or "approximately", etc) ... i am now remined of sienfeld episode about exclamation point usage! lol
 

·
The Biggest P0st Whore!!
Joined
·
2,912 Posts
Basically the over heating over 35 would be due to the engine generating more heat at higher speeds and not having enought radiator passages/surface area to dissapate the heat. Try driving around with the windows down and heat and blower on high (bad time of year I know). If that helps the problem I would suspect the radiator. If it does not look at the hoses and then the water pump. At higher speeds worn hoses might collapse causing a reduction in coolant flow.

Didnt know about the architectural shorthand. I'll keep that in mind in the future.
 

·
The Biggest P0st Whore!!
Joined
·
2,912 Posts
To check if the radiator is cloged drive the car till it is warm and then check the temp of the radiator. If it is functioning well the temp should be highest at the water inlet and be close all the way across. If it is not then there will be a section at the top/middle/bottom or some combination of the above that will be cold and the rest will be really hot. on our cars an IR thermometer would be a good way to check. Otherwise you could pull the fan shroud in order to get a hand on the radiator.

Good

Bad
 
1 - 5 of 5 Posts
Top