Author Topic: Running hot (not fan clutch or bleeding problem) (Read 5960 times)

t la · « **on:** February 08, 2011, 10:39:49 PM »

So I got my car in april, ever since i had started driving it the car would get up to temperature, then move slightly above the half mark and usually stay between the half and 3/4 mark.

I did the mess under the intake reroute, flushed and bled coolant, replaced the coolant pipe attatched to the block and replaced the t stat... was still running over the halfway. (It got even hotter when traveling uphill also)

The car was then on stands from september untill winter replacing all brake components and bushings while applying for college (hence the duration of a simple project)

Now that it is winter the car runs just below half or pretty much dead center, so it seems like there is maybe some type of pressure leak or the system is just slightly off somehow... any ideas?

I've searched this problem like crazy but everyone's problem has been fan clutches, which i honestly doubt this is....

thanks all

colin86325 · « **Reply #1 on:** February 09, 2011, 09:55:43 AM »

Sometimes the gauge can display incorrectly, usually erring on the side of too hot. Try to bang on the dash near the gauge and see if the temperature changes. If so, you should clean and retighten the nut on the rear of the gauge.

doitover · « **Reply #2 on:** February 09, 2011, 10:24:14 AM »

Mine with no fan does pretty much what you describe. The fan clutch is easy to test so probably a good idea to do that. I'd google around for a description but I think it is something simple like sticking rolled up newspaper against the fan with the car idling. If it stops the blade, the clutch is bad.

I've also seen similar behavior from not having done a complete bleed but it would always eventually run high.

If you had any sort of leak you would see your coolant level go down.

Other than those two things about all that can go wrong would be a clogged radiator or bad thermostat.

t la · « **Reply #3 on:** February 09, 2011, 02:47:09 PM »

t stat was replaced, i suppose i'll look into the fan clutch but i honestly doubt that is the problem.

the temperature gauge does move when i bang on it but sometimes it moves hot and sometimes cold so i think it's more of an issue that it sticks than one of it not really working..

dakon · « **Reply #4 on:** February 10, 2011, 07:56:09 PM »

did you pressure test your coolant system?

you can also do a leak down test.

Either of these tests would help you determine if there could be a blown head gasket, or a cracked head.

depending on how old your rad is Doitover could be on to something. If you have an air compressor you could put some compressed air though the Rad see if you get a decent amount of flow. You can also take the Rad to some placed to get it "properly" tested, you would have to call some shops in your area to figure out where to take it.. however the Rad for the M42 is actually not too expensive..

Is your expansion tank level varying? is the level constant over a week or more? if you are loosing any coolant there could be a problem with the head....

good luck.

Also you can get a leak down tester from harbor freight for like 30 bucks, it does require an air compressor though.

t la · « **Reply #5 on:** February 11, 2011, 02:30:22 PM »

coolant has been consistent since september, so i'm thinking it could be the radiator, what exactly does the leak down tester do? I have access to a compressor for it.

DesktopDave · « **Reply #6 on:** February 11, 2011, 04:32:00 PM »

You're saying the temp is dead center? Mine takes a while to warm up, but eventually it sits right in the middle, maybe a hair above. When I got the car it tended to get really hot especially at speed (nearly to the red), but once I bled it a few times it seems perfect now. A new thermostat should cure the slow warm-up.

t la · « **Reply #7 on:** February 11, 2011, 10:23:35 PM »

yes mine sits to the right of center in summer, just left in winter. but i've already bled and gotten a new t stat.

DesktopDave · « **Reply #8 on:** February 12, 2011, 08:21:12 AM »

It all seems OK to me, just the way you'd want it. The only downside is that a colder engine uses a bit more fuel. Keeping it cool will make it last.

BTW, which thermostat did you install, the 80degC or the 88degC?

t la · « **Reply #9 on:** February 12, 2011, 10:23:09 PM »

88deg

Balleristic31 · « **Reply #10 on:** March 23, 2011, 05:37:37 PM »

have u tried tightening the gauge ground on the back of the cluster

Carib · « **Reply #11 on:** July 18, 2011, 01:25:40 PM »

t la,

Any updates regarding your issue?
My '91 318i is experiencing the same issue where the gauge is now going over the 1/2 way mark when sitting in traffic and/or when going up hill/engine under load. I've bled the system several times, the coolant level is constant, I've checked the connections for the temp gauge in the instrument cluster. Also tested the fan and it works fine.

Anyone has any other suggestions?

Thanks,
Carib.

DesktopDave · « **Reply #12 on:** July 18, 2011, 05:44:43 PM »

I'd be sure the temperature sender is within spec. I'd also jump the connections on the fanstat switch (side of the rad) to be sure it's OK. If you have no idea how old the rad is I'd also pressure test the system and (carefully) be sure the bleed screw o-ring is still intact.

Temperature does normally go up when load does, but the gauge will never let on. IMHO that dead-center temp gauge is a bad decision on BMW's part.

Which fan did you test, the engine driven or the aux fan?

E30King · « **Reply #13 on:** July 18, 2011, 06:31:32 PM »

Definately look into the clutch fan. My E30 325i had the same issue before, it turned out my thermostat was broken (like actually broken physically) and my clutch fan was getting tired. Replaced those, ever since the temp has been sitting at centre in any condition. It used to climb up past centre when everything was screwed up.

With my 318iC ,my temp is sitting at middle (we just replaced the head and such), and will just go slightly past, but then go back down to the middle and sometimes just below middle. I thought it would be a problem, but I'm getting full circulation of cooling through the system. I also replaced the fan as it was wobbly so it had to be anyways, still the same. I don't think it's entirely a big issue, you're gauge is probably fooling with you.

Carib · « **Reply #14 on:** July 19, 2011, 02:34:37 AM »

I tested the aux fan. The radiator is less than a year old. Replaced it myself as the old plastic one had cracked. The thermostat was changed about 3 months after the radiator. It had failed and was stuck in the open position. Got the 88deg thermostat installed. Did that myself as well. Had to bleed the system several times on both occasions to get all the air out. Checked the bleed screw this evening and it's in good condition.

Whilst driving home today the temp needle creeped past the halfway mark again and kept on going. Turned on the heater full blast for about a minute. This got the temp needle back down to the middle of the temp gauge and it stayed there for the rest of the 15min drive back home.

Will check the fan clutch... will update with the results of that.