M52B28 in heat

[martijn76]

I've got a problem since my M52 conversion and I'm a bit lost as this point.
The engine: I used a e30 sensor, big rad, new pump, new thermostat, etc. I capped off the throttle body pre-heat.
Vented a dozen times, lifted the front, interior vent on heating.
All the hoses are hot, interior gets warm.
When driving slow(50km/h) the temperature goes to 3/4 on the gauge and the fan brings it back to normal. This shouldn't happen when driving.
Even at 80-100 km/h (60mph) the temperature goes further than 1/2.
There's no sludge in the oil, no oil in the cooling liquid.
Is this a symptom of a cracked head or maybe normal for a e30 m52?
Any ideas?

[jimbom30cab]

What temp stat have you used, 80 degree is recommended iirc

[Brianmoooore]

Sounds like a combination of an inadequate radiator and an 88 or 90 degree thermostat.

[DanThe]

M52 standard stat is 92 degrees C, which will send the E30 gauge up to 3/4
Use an 88 or 80 stat

[martijn76]

I used an e30 88 stat, the radiator is a Behr 328i aircon.
The rad gets hot before the gauge is on 50%.
What engine uses a 80 degrees stat?

[Motorhole]

2.0-litre M50 iirc. Try E34 525i with M50 engine or early E36 325i. Realoem is your friend

[Brianmoooore]

Don't understand why anyone would want to run an 80 degree 'stat.
An engine runs more efficiently the hotter it is, and the limiting factor is local boiling at the hottest points in the head. Presumably, the M5x heads are a better design compared to the M20 heads in this respect, with less 'hot spots' and so can run hotter coolant.
The gauge sitting just past halfway equates to 88 degrees, and the needle should quickly rise to there after start up (within a mile) and then stay there. If it rises significantly, then there's a defect in the cooling system.
Has the engine been checked for a defective (plastic rotor-ed) water pump?

[martijn76]

The engine had a metal rotor pump, I bought a new pump but that didn't make any difference.
To recap; every item that can be replaced in the cooling system, was bought new at BMW, accept a couple of hoses, all we're clean inside.

[Demlotcrew]

Cooler engines are more powerful Brian

[Brianmoooore]

Cooler engines are more powerful Brian

Not be any amount that anyone'll notice in the real world!

[327ire]

You might have already mentioned this but how is the ducting around the rad/ fan/ valance opening? Also the center grill can either be open vented or closed. I stuck an m52 in my 316i and noticed the middle grill in front of the rad was solid. The 316i valance has only 1 opening so opening that up helped me to.

[ross_jsy]

Cooler engines are more powerful Brian

Not be any amount that anyone'll notice in the real world!

Sort of like the efficiency gains from running an engine hot.

I would much rather have a few more degrees "safety net" to spot the temperature gauge rising in the event of part of the cooling system failing than a fried head

[AndyZippy]

^ Yea, this is why i am running an 80 deg thermostat, much happier running with that than the 88deg i had put in. However, i can switch back to the 88deg for the coldest months of winter if i feel i need to.

80 deg, by the way, is indeed from an M50 2.0.

[DanThe]

Just for comparison, my E39 540i runs at 110° for "efficiency"
The exploding hoses and cracked rad dont seem to be very efficient at doing their job

Oh, and my average mpg is 13.7

Good old mechanical 87° stat is on its way

[E30BeemerLad]

Oh, and my average mpg is 13.7

Sublime

[martijn76]

I measured for CO in the coolant and there's none
What I did noticed is that the coolant level in the expansion tank rises when I leave the cap off, like pressure is being build up in the engine, like with a blown head gasket.
I'm gonna remove the pump, stat etc and see if I can find a mechanical problem.

[Brianmoooore]

If you remove the pressure cap, you will lower the boiling point of the coolant by about ten degrees Celsius, and local boiling is likely to occur at the hottest parts, pushing the coolant level up in the bottle.

[martijn76]

I took the cap off before start, so the boiling point didn't change. I never started up without the cap on, so could be normal.

[DanThe]

Oh, and my average mpg is 13.7

Sublime

You love it

[Brianmoooore]

I took the cap off before start, so the boiling point didn't change.

Exactly, but the engine is designed to run with a boiling point that does increase by several degrees, as the engine comes up to running temperature.
Take the cap off when the engine is up to temp., and you're likely to be posting from the burns ward of your local hospital.

[hash]

I have the same problem with my e30, even without a thermostat in place still creeps up during general driving but have tested for co2 in coolant and it's fine. I am using the same setup as you so if you resolve please let me now. Good luck.

[martijn76]

I took the stat-housing and stat off, filled the engine with coolant, replaced the stat(although it was brand new) after I drilled a tiny hole in it.
While driving the temperature is in the middle now, as it should be.
So I think the problem is solved.
Now some warmer weather please to test it properly.