S52 running at 250deg F water temp

[SS350]

I've been working on wrapping up my S52 conversion and was screwing around trying to get the stock coolant gauge cluster to work, I double checked all of the wiring to the 2 coolant sensors (i was measuring off the brown/orange top) then I finally put an autometer water temp gauge in.

I have bled out the system (i think) and have a Spal 1600 cfm puller mounted behind the M20 radiator.

After a lot of searching here and on bimmerforums in the race and E36 sections they say that on a HOT day,on the track... they see 220 F water temps.

How am I seeing 250F in 32 deg F weather in New England.

80 deg C~178F Thermostat is new, water pump is metal version (but not new), I checked the oil - water doesnt seem to be mixing....

Hopefully these brief stints to 250 are not going to warp my head or ruin the head gasket... so far no external leaks and engine seems to be running strong.


of note - the autometer sensor is mounted in a zionsville tap that runs in the throttle body circuit, not in the head...


any ideas guys?? buy a stewart racing pump??

[SS350]

Also, another thing that had me thinking it was a air bleeding issue is that the HEATER only blows hot air SOMETIMES

[scrubed]

clean and flush coolant? Possibly a bad heater core or clog somewhere in the system?

[hoveringuy]

Is the radiator outlet hose (pax side) getting hot?

[richardb]

Sounds to me like you have an air pocket in the system. Open the radiator cap and put the front end up in the air on jack stands and let it run, as the air pocket burps itself out you will top up the coolant. If that doesn't work and the temps start going up high shut it off so it doesn't overheat, theres probably something else going on.

[flyboyx]

by the sounds of it, you are running a stock sensor with an aftermarket autometer gauge? if this is the case. the resistance probably is off. that is to say that the gauge and sender are not compatible. do you have any indications that the engine is actually overheating? it should blow out the cap with tons of steam at that temp. if everything is basically normal except you see a high reading on your aftermarket gauge, you can be pretty certain that is the problem.

[SS350]

1st off thanks for the ideas guys....

clean and flush coolant? Possibly a bad heater core or clog somewhere in the system?

heater core was new last year... I suppose anything could happen tho and it or Something else could be clogged.... If the HVAC mix valve was not opening it would not effect the core correct??

Is the radiator outlet hose (pax side) getting hot?

The radiator outlet hose passenger side bottom, does get a little warm after the temps reach 200ish... but not as hot as the drivers (LH side) engine outlet hose...

Sounds to me like you have an air pocket in the system. Open the radiator cap and put the front end up in the air on jack stands and let it run, as the air pocket burps itself out you will top up the coolant. If that doesn't work and the temps start going up high shut it off so it doesn't overheat, theres probably something else going on.

i had it parked on a hill on ramps, but i didnt have the cap open (so i probably had the procedure wrong).... i DID however run the car with the cap open and hold the radiator up off the support (no fan mounted) so that the over-flow vent tube on the radiator was the highest point... it bubbled a bit and once it hit 180... 190 200 after about 15 mins it started to gurgle out a lot... was that air or a boiling system expanding???

by the sounds of it, you are running a stock sensor with an aftermarket autometer gauge? if this is the case. the resistance probably is off. that is to say that the gauge and sender are not compatible. do you have any indications that the engine is actually overheating? it should blow out the cap with tons of steam at that temp. if everything is basically normal except you see a high reading on your aftermarket gauge, you can be pretty certain that is the problem.

I am running the temp sensor that came with the autometer gauge. The calibration COULD be off, I have thought about it...

the indication that it is overheating is that the radiator overflow is blowing out when it gets that hot, which could mean that air is working it self out of the system but blowing out coolant at the same time, or i am in fact overheating...

i tried to get the stock temp gauge to work, brown top sensor, checked the continuity and the wiring on the engine to body harness... it could have been the actual cluster gauge.... but it worked no problem before i took the engine out and i decided I wanted to read the actual temperature anyways....



So thanks guys... im gonna keep looking around... could the metal water pump impeller really fail??? my oil did not look like water got into it, was not light brown and goopy.... so i dont THINK thats the issue, but i have added a TON of water/antifreze to this damn system. Maybe the air bubble is in there and REALLY stubborn... and I keep bubbling it out and overflowing and then going low again....

maybe my gauge is just wrong...

[hoveringuy]

The radiator outlet hose passenger side bottom, does get a little warm after the temps reach 200ish... but not as hot as the drivers (LH side) engine outlet hose....

That sounds completely normal. Coolant is flowing and the radiator is ... cooling.

My temperature sensor is in a non-standard location so I used one of those infrared laser thermometers to cross-check it.

I think if it were actually at 250 it wold be running like crap as the ECU pulls the timing.

[SS350]

That sounds completely normal. Coolant is flowing and the radiator is ... cooling.

My temperature sensor is in a non-standard location so I used one of those infrared laser thermometers to cross-check it.

I think if it were actually at 250 it wold be running like crap as the ECU pulls the timing.

I think thats a good idea, maybe the sensor being in the throttle body cooling cicuit is screwy and i SHOULD have drilled and tapped the head (only didn't because I didn't want to have metal shards in the engine...)

to your other comment... It seems to run MINT... I got in the car at 190 (per the gauge) and took it out of the garage after the 4th or 5th time of trying to bleed.... and took it up the driveway and up the street (~1/4 mile)... going UPHILL the heater blew some really nice hot air.... and the engine was pulling great... got to the top of the hill and turned around came back (as the temp had reached 250 per the gauge pretty quick on getting up to speed).... and brought it back home...

I have too many what-ifs bouncing around in my head...

[SS350]

If the heater core valve were only open sometimes (OR if it was broken in the closed position somehow - even without power being sent to it)... and sometimes blowing hot air, but other times blowing cold air.... I wouldn't be bleeding the system adequately.... right?

It’s just a thought... I'll look into how it works in the bentley and test her up...

but yes the top hose does feel hot... while the bottom does feel cooler...


***when you bleed these cars with DOHC's, you want the front end jacked up, such that the overflow vent is higher than the resevior... and I need to run the car such that it reaches operating temperature and bubbles come out of the overflow resevoir? Correct??

how do i account for the fact that the coolant is heating and expanding? as it heats and overflows just keep adding coolant???


thanks guys.... such a possibly simple thing to hold it up!! :???: