87 325IS doesn't like track...?

Hey guys! I own a 1987 325IS and I finally lost my SOLO 2 "virginity". The car ran great and I love the sport, but the car was running hotter then expected. I have a good friend who knows these cars inside out, and I remember he had once said that the temp sensor usually never reaches the center unless your really pushing it, and mine had been at the three-quarters mark or farther... The car has plenty of coolent, and the only other thing I can think of about that race was that I was deffinitely pushing the car (5500-6000 rpm in second gear) but I didn't think the car would have such a reaction. oh, and the car has close to 250000 miles on it. Thanks for any help you guys can offer!

Originally Posted by Ben T

Hey guys! I own a 1987 325IS and I finally lost my SOLO 2 "virginity". The car ran great and I love the sport, but the car was running hotter then expected. I have a good friend who knows these cars inside out, and I remember he had once said that the temp sensor usually never reaches the center unless your really pushing it, and mine had been at the three-quarters mark or farther... The car has plenty of coolent, and the only other thing I can think of about that race was that I was deffinitely pushing the car (5500-6000 rpm in second gear) but I didn't think the car would have such a reaction. oh, and the car has close to 250000 miles on it. Thanks for any help you guys can offer!

Fan clutch maybe.

put in a lower temp t.stat and do an electric fan conversion. if youre gunna race it, do a dual fan setup, one push one pull both offset from the other. probably 2 12" fans. use one for low and the other for a high.

Originally Posted by downhiller

put in a lower temp t.stat and do an electric fan conversion. if youre gunna race it, do a dual fan setup, one push one pull both offset from the other. probably 2 12" fans. use one for low and the other for a high.

That is a band aid. A stock setup in proper working order will handle track duty.

New larger radiator and use only genuine coolant. Change the sender for the gauge.

Originally Posted by BMWFatherFigure

New larger radiator and use only genuine coolant. Change the sender for the gauge.

Band-aid

Originally Posted by markseven

That is a band aid. A stock setup in proper working order will handle track duty.

i notice a slight increase in temp when i ran mine hard and my fan clutch was fine, with a new water pump and a 60/20/20 mix of water/coolant/redline wetter water. did the fan delete and ran the aux fan on high and temp never went over half way between 1/4 to 1/2 way.

plus doing the electric conversion will help free up some power, along with an ac delete.

With certain types of bad Head gaskets, the coolant temps stay normal when the car is operating in the street, and even when driven enthusiastically on the street.
However, when the engine is exposed to sustained high loads and RPMs, the cylinder nearest the weak spot in the gasket pumps air through the bad spot and into the coolant circuit, causing coolant temps to spike. When the engine cools off, the coolant may leak into the cylinder.

The coolant system should be pressure checked, and a leak down test performed on the cylinders.
Until these items are judged healthy, any work on the cooling system may be a band aid until the engine is again in a sustained high load state.

m

Originally Posted by 7pilot

With certain types of bad Head gaskets, the coolant temps stay normal when the car is operating in the street, and even when driven enthusiastically on the street.
However, when the engine is exposed to sustained high loads and RPMs, the cylinder nearest the weak spot in the gasket pumps air through the bad spot and into the coolant circuit, causing coolant temps to spike. When the engine cools off, the coolant may leak into the cylinder.

The coolant system should be pressure checked, and a leak down test performed on the cylinders.
Until these items are judged healthy, any work on the cooling system may be a band aid until the engine is again in a sustained high load state.

m

a bad hg is a bad hg. the only difference between a normally operated engine verses the same one being raced, is its at higher rpms more often. however, its still within the manufacture specs on combustion pressure. so if a hg is leaking while racing, its gunna leak driving around on the streets as soon as it gets to op temp.

theres 2 main ways a hg can fail, which either leaks all the time, or only leaks when the cooling system gets to pressure. not if your driving down the street vs racing.

Originally Posted by downhiller

a bad hg is a bad hg. the only difference between a normally operated engine verses the same one being raced, is its at higher rpms more often. however, its still within the manufacture specs on combustion pressure. so if a hg is leaking while racing, its gunna leak driving around on the streets as soon as it gets to op temp.

theres 2 main ways a hg can fail, which either leaks all the time, or only leaks when the cooling system gets to pressure. not if your driving down the street vs racing.

I only offer suggestions based on experience.
Yours appears to be limited.
A casual "slap a couple of fans on it" is not much help, is it?
Read up a little more on the effect of rising temps on dissimilar materials that are bolted together.

m

Originally Posted by 7pilot

I only offer suggestions based on experience.
Yours appears to be limited.
A casual "slap a couple of fans on it" is not much help, is it?
Read up a little more on the effect of rising temps on dissimilar materials that are bolted together.

m

i mainly raced drags, so thats where the fans come from. but i never once had a problem from running a single stage fan or the stock when i decided to run the track. even on autox runs i just didnt turn the fan on. sorry my experience is limited cause my car was working just fine with my band aids.

I would not call a larger radiator 'band aid' either. Change the temp sensor. My road cars sit at exactly half not matter how hot outside with or without air con running. Once a sender has been cooked they are unlikely to be as accurate.

Originally Posted by BMWFatherFigure

I would not call a larger radiator 'band aid' either.

Basically you are saying that the stock cooling system, even in good working condition, is not suitable for autocross duty, correct?

Yes. Regard my suggestion as 'overkill' maybe, BUT NOT 'band aid'

Originally Posted by BMWFatherFigure

Yes. Regard my suggestion as 'overkill' maybe, BUT NOT 'band aid'

You are probably one of two people that feel the M20's cooling system cannot keep up with the demands of an autocross. All two minutes of it. At less than 60 miles an hour.

OP, a bigger radiator is addressing the symptom, not the problem.

Originally Posted by markseven

You are probably one of two people that feel the M20's cooling system cannot keep up with the demands of an autocross. All two minutes of it. At less than 60 miles an hour.

OP, a bigger radiator is addressing the symptom, not the problem.

Didn't mean for this to be mean

what about a bad pressure cap? if it doesnt hold the pressure as well, lower coolant pressure, higher temp.

OK, I refer to the BMWCCA / Bentley publication 'BMW Enthusiast's Companion' page 81. Inter alia 'substandard radiators from Behr Radiator of Mahwah, New Jersey.' Also 'BMW radiators are too small in capacity and a constant source of grief to owners.'
Ben T wants to race, high rpm (horsepower / heat). Although he has not quantified the higher gauge reading or changed the sender he thinks the engine is running too hot. By all means change the water pump, thermostat, radiator cap and hoses but for his application I believe a larger radiator is prudent.
Having crewed for a race team in Western Australia (it gets hot here) we ran oversize radiators compared with the same engine in road use without problems. Also from his OP his gauge is not behaving normally - change sender.

I will take you a bet that if you run a mildly modified 325 E30 over 100 mph (pleny of airflow) for over 20 minutes, you will see it overheating !
Of course this is in our balmy temperatures where it hardly drops under 100 F in summer
Anybody who builds cooling systems knows that you wan more liquid capacity in the radiator
If possibile increase the frontal surface area, but try not to add another core.
Thicker can block airflow
But this is hadly of refference for somebody racing short distances in a cool climate

So Ben T is from Alberta. Does he even need a radiator? If he is having overheating problems (according to his iffy gauge) then he needs a cooling system overhaul. If he is going that far and the radiator is proving to be inadequate AND he is going racing fit a larger one. Its not rocket science.

stock cooling system in 100% order will be fine, but if you want to run cooler and add safegaurds which are of course recommended for a dedicated track car seeing sustained high RPM, then upgrades may be required

So far a great help guys! Thanks so much! I forgot to mention that I have already replaced some of the hoses and the water pump, temp sensor and the fluid. If it makes any difference (which I'm not sure if it would) I also have added in a sports chip in the car. The head gasket I beleive is fine, as we checked it, but that was over 3000 kms ago... cylinder pressures are all normal too, they were checked at tops 1000 kms ago. Raiator has crossed my mind as a source of the issue, but more because it looks relatively old and (knowing the previous owner) not very well cared for. After the drive shaft replacement, the radiator is likely the next thing to get checked by next summer. After all, overheating in Alberta during the winter? on a side topic, does anyone also have any ideas on places to get a driveshaft redone or where to just purchase a whole new one entirely?

I have just started thinking (which is not a good thing)
The temperature gauge measures the temperature after the Thermostat going to the radiator on my 323
On most cards the Temperature is measured before the Thermostat, on the engine side.

Now in your arctic conditions you could have the content in the radiator freeze up causing the car to overheat. I'm sure you know that better than me.

Maybe the cold outside air is keeping your temperature gauge up ?
I had this on Buick V6 motors that needed a long cycle of hot-cold-hot-cold before stabilising on our -5 C winter mornings. This was with a very quick responding gauge & I would think the MotoMeter gauge would be a lot more dampened, showing you tempertaures that are not current

The thermostat is also responsible for keeping the water circulation at a constant rate !
You can get the water overheating in the head & block if you run certain engines without thermostats, as the water circulates too quickly to absorb & transmit the heat.

I have been suffering with heat related issues for most of the past 19 years and realised it is not einfach...

Originally Posted by BMWFatherFigure

So Ben T is from Alberta. Does he even need a radiator? If he is having overheating problems (according to his iffy gauge) then he needs a cooling system overhaul. If he is going that far and the radiator is proving to be inadequate AND he is going racing fit a larger one. Its not rocket science.

This full version of this pic has been on my desktop for months. I just now realized that it may be revealing for this thread, the focal point being the M10-size radiator. The car on the right made upward of 320hp.