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Old 03-13-2018, 02:27 PM
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Default Still overheating after overhaul - e36 m3

I am in need of some help troubleshooting an overheating issue with my 98 M3.

First off some history. I have had the car for ~3 years and 30k+ miles, it is currently sitting at 213k miles. Last complete cooling system overhaul was around 165k, when a the top end was also rebuilt. I have had no engine issues.

I use a scan gauge to monitor coolant temp and typical highway temps are around 196-198 and stay around the same when stopped (never over 202-204). A month or so ago while in carpool to drop the kid off the temp starting going up and hit 220 before I was able to get out of line an moving to drop the temp.

Fan clutch maybe or air in system? Bleed it and put in new fan clutch, same problem.

I was due for a cooling system swap anyways (every 60k) so I went ahead and ordered everything. I replaced the following:
Radiator
Water Pump
Thermostat & Housing
Reservoir and sensors
All hoses, tensioners & belts

I have bleed the system once so far but I am still getting the temperature increase when the car is not moving. My main concern is that the upper radiator hose is easy to squeeze once the car is at temperature, I thought it should fill with fluid once the thermostat kicks in and be stiffer? Is that correct?

I am going to bleed it again and check the fan clutch this weekend but figured I'd seek some advice since I don't have time to work on it during the week.

Some other notes from the swap:
-Coolant came out clean
-There was some white build up at the thermostat housing but I don;t think this was electrolysis damage (Picture attached)?
- The engine block drain plug had some residue and maybe rust on it, the hole in the engine block also showed some corrosion. There was some corrosion inside also, I scrapped out what I could but didn't see a way of cleaning it.


Any help is greatly appreciated.
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Old 03-13-2018, 06:04 PM
HughA44s HughA44s is offline
 
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Not sure of the exact cofig of the e36M3 but getting the front end in the air (1.5 to 2 ft) above the rear wheels always helps. Also make sure the heater is turned to max. So on a e46 m3 its stick the nose in the air a bunch, loosen the bleed screw, and fill until it comes out the bleed screw - tighten bleed screw. After that, drive until warn - then stick the nose in the air again, then bleed pressure until no air.
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Old 03-13-2018, 08:01 PM
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Did the old pump come out in one piece? Check the radiator in various spots with an infrared thermometer.
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Old 03-13-2018, 08:06 PM
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Thanks for the feedback.

When I bleed it again I will raise it up and I did have the heater on max.

The old pump came out in one piece and looked good. I will check out the radiator with the IR gun as well as the fan clutch.

Any idea about the upper radiator hose? It just didn't feel like fluid was going through it. I may pull that off before I warm it up again just to see if its wet.
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Old 03-13-2018, 08:15 PM
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Hopefully/likely you arent moving fluid because of a big air pocket. Assuming thermostat is in right and no blockages (old pump vane) with a new radiator.... is the upper hose is dry, remove the radiator end and fill it up. This has worked for me. yes it is messy.
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Old 03-13-2018, 08:17 PM
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Quote:
Originally Posted by HughA44s View Post
Not sure of the exact cofig of the e36M3 but getting the front end in the air (1.5 to 2 ft) above the rear wheels always helps. Also make sure the heater is turned to max. So on a e46 m3 its stick the nose in the air a bunch, loosen the bleed screw, and fill until it comes out the bleed screw - tighten bleed screw. After that, drive until warn - then stick the nose in the air again, then bleed pressure until no air.
that. sort of.
only needs a foot of altitude.
fill, open bleed screw, AND LEAVE IT OPEN while the car warms up. do not close until you get a solid flow of coolant out of it. keep checking the coolant tank to make sure it is full.

let car warm up with heat on. check to make sure heater is making warm air.


sounds like you have air in the system.

and make sure the electric fan works.
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Old 03-13-2018, 08:32 PM
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You probably know this, but many temp gauges go to full hot if the coolant level goes below the temp sensor...
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Old 03-13-2018, 10:42 PM
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If it is happening with the car sitting at idle it is likely the fan clutch. But should check coolant bleed first. Basic e36 don’t have a bleed valve not sure on m3. Just fire it up with front end elevated. Keep the cover off the fill cap and raise rpm to 3000 or so for about 10seconds. Fill more coolant. Repeat 3 or 4 cycles. Put on cover and see if the temp Guage stays in middle. Turn off and allow to cool. Repeat as needed.
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Last edited by 86911TLCAB; 03-13-2018 at 11:18 PM.
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Old 03-14-2018, 01:06 PM
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All e36's have a bleed valve unless someone modified the expansion tank. It's the phillips head screw right beside the coolant cap. It will even have a little tab around it that helps to keep parts together. Jack up that front end and just keep pouring in and flowing out coolant while squeezing the hoses. It takes a lot of coolant because so much will be coming out. You are getting hot while sitting still which means you have low flow for one of many reasons already stated - doubtful the fan is bad or it would be obvious while you are examining what's going on. Worse case scenario - head gasket going up, but hopefully just bad flow due to some blockage or not enough coolant. If anyone ever put Bars Leak in your car, you have a ton of flushing to do.
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Old 03-14-2018, 06:39 PM
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I suppose I have never considered that screw a bleed screw. I see opening that the same as opening the fill cap. But keep filling it and squeezing the hoses. If there is an air bubble it will make its way out of the system. Had a similar issue on my e36 recently.
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