Pushing Coolant

Z32 · Dec 27, 2006

Hi, a few days ago I noticed that my car started to push coolant into the overflow reservoir, so I did some tests and heres what I found:

No oil in coolant
No coolant in oil
Compression is perfect
Cant see any smoke when driving

Only seems like it's pushing coolant under boost, also my water temp gauge is acting funny. If I drive normal without boosting it's below what it usually was, once I step on it and boost, the gauge needle goes more than half of the gauge. yesterday I hooked up my laptop and started logging my coolant temps. I drove without boosting and it was running at around 175(I have 180" thermostat, koyo radiator and 18 PSI coolant cap), but usually it's 184. Then all of a sudden it went up to 189 and back down to 175 and then the whole way home, the line on the logger was shaking back and forth from one degree to another(never seen it do that before). I think it was cycling between 178/181/184. Could it be just a faulty thermostat or water pump? Or do you still think it's a headgasket? Help would be greatly appreciated. Thank You.

TurkF26 · Dec 27, 2006

Sounds like your coolant temp sensor might be going bad? I dont think it would be your headgasket but i could be wrong but it sounds like your temp sensor is either bad or going out.

Talesin · Dec 28, 2006

Depends on how much coolant you're pushing. Try letting the engine get cold, then starting the car. With a good HG, the water should be fine. With a minor leak from a cylinder into the watering system, you'll get a bit of a burble. With a warped head or a severe HG breach into the coolant, you can get a geyser high enough to splash the hood.

Remember that ECU logged temperature and cluster temperature are two seperate sensors. It's less likely that one is going bad, if both display erratic behaviour in a certain situation.

If it's only under boost, and you're still on the MHI oil/water center spool, I'd go for the semi-obvious one(s); either the pressure is getting into the water system from your turbo, or you might have a very minor HG leak that only blows into the watering system under boost.

Easiest way to check for the HG problem is to pop off the radiator cap and do a leakdown test (pump pressurized air into each cylinder) and watch the radiator for water-rise or bubbles.
The turbo is more difficult... easier to just get it rebuilt; most that are under daily use could use a rebuild every couple years anyway. Best clue would of course to be to watch for white or blue smoke.

Z32 · Dec 28, 2006

What if I do a hydro carbon test in my water neck, would that tell me if my HG is going bad?

twack · Dec 28, 2006

This happened to me and it truned out to to need a new thermostat and radiator

freshlane · Dec 28, 2006

Did you recently change the coolant? If so you may have air in the hoses

TURFNNSURF · Dec 28, 2006

Z32 said:
Hi, a few days ago I noticed that my car started to push coolant into the overflow reservoir, so I did some tests and heres what I found:

No oil in coolant
No coolant in oil
Compression is perfect
Cant see any smoke when driving

Only seems like it's pushing coolant under boost, also my water temp gauge is acting funny. If I drive normal without boosting it's below what it usually was, once I step on it and boost, the gauge needle goes more than half of the gauge. yesterday I hooked up my laptop and started logging my coolant temps. I drove without boosting and it was running at around 175(I have 180" thermostat, koyo radiator and 18 PSI coolant cap), but usually it's 184. Then all of a sudden it went up to 189 and back down to 175 and then the whole way home, the line on the logger was shaking back and forth from one degree to another(never seen it do that before). I think it was cycling between 178/181/184. Could it be just a faulty thermostat or water pump? Or do you still think it's a headgasket? Help would be greatly appreciated. Thank You.

The coolant temp fluctuations are normal, as the coolant heats up in the motor it opens the T-stat and flows to the radiator, then as it cools in the rad and gets pumped back into the motor it starts to close the T-stat building pressure and heat, to start the cycle again. This is why running without a T-stat is BAD, if the coolant can't stay in the rad long enough to cool before returning to the motor, you will eventally overheat the engine.

If you are only filling the overflow bottle after boosting the car, I say it's the Headgasket. I dealt the exact same problem for 4 months, new radiator, Thermostat, coolant flush, water wetter. nothing helped and I only pushed coolant after boosting over 15psi. The sniff test couldn't find HC's because the system only leaked under boost. Finally I took the car to JNZ Tuning and had Josh pull the head, He found two small blow-out spots from cylinder 2 and 4 into the water jacket lines. They were small enough to hold comperssion at normal driving, but couldn't hold the cylinder pressure in under boost.

Try burping the system first, then try the sniff test. Even a new T-stat they are cheap enough, It can't hurt. Even try a compression test to be sure. Lastly you could try a pressure test on the cooling system, leave the spark plugs out of the motor to see if any pressure is lost into the cylinders from the cooling system.

Good luck, but Im 98% sure it will be the headgasket.

GST with PSI · Jan 1, 2007

TURFNNSURF said:
The coolant temp fluctuations are normal, as the coolant heats up in the motor it opens the T-stat and flows to the radiator, then as it cools in the rad and gets pumped back into the motor it starts to close the T-stat building pressure and heat, to start the cycle again. This is why running without a T-stat is BAD, if the coolant can't stay in the rad long enough to cool before returning to the motor, you will eventally overheat the engine.

If you are only filling the overflow bottle after boosting the car, I say it's the Head gasket. I dealt the exact same problem for 4 months, new radiator, Thermostat, coolant flush, water wetter. nothing helped and I only pushed coolant after boosting over 15psi. The sniff test couldn't find HC's because the system only leaked under boost. Finally I took the car to JNZ Tuning and had Josh pull the head, He found two small blow-out spots from cylinder 2 and 4 into the water jacket lines. They were small enough to hold comperssion at normal driving, but couldn't hold the cylinder pressure in under boost.

Try burping the system first, then try the sniff test. Even a new T-stat they are cheap enough, It can't hurt. Even try a compression test to be sure. Lastly you could try a pressure test on the cooling system, leave the spark plugs out of the motor to see if any pressure is lost into the cylinders from the cooling system.

Good luck, but I'm 98% sure it will be the head gasket.

How about starting simple and performing a boost leak test????

If the car is only pushing coolant under boost why don't you simulate the condition and see where your boost is going? Pressurize the coolant system at about 15psi And find your boost leak. Your problem will be at the source of the leak. Agreed, it could possible be a head gasket along with a hundred other things.

I'm not sure what a "sniff test" is but testing for HC's in the coolant system is definitely a good idea. You can buy a kit at any parts store to do this. It's much like a home pregnancy test ( LOL

). Just put some coolant from your system into a beaker mixed with a detection chemical and see if it changes colors. If it changes you have HC's in your system (AKA compression leak Etc.). Bad news.

Good luck....

The Top DSM Community on the Web

Pushing Coolant

Z32

TurkF26

Talesin

Z32

twack

freshlane

TURFNNSURF

GST with PSI

Similar threads

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds