any one out there have any good ideas for diagnosing coolant leaking into the combustion chamber started car today ran sweet for about 5 minutes then idle dropped to about 500 almost stalling give a good rev idles fine again for about 5 minutes then idle drops again it may have been coincidence but radiator level light came on and car took about 500mls to fill up from what i can tell doesnt appear to be leaking combustion into coolant system because its not presurizing the cooling system think its leaking coolant into combustion any ideas

 

If the coolant is leaking into the combustion chamber, it will burn along with the air/fuel mixture. Burning coolant will cause a thick white cloud of smoke to appear from the exhaust. I'm talking about a James Bond smoke screen. The exhaust will also smell like coolant.

If you are loosing coolant and its not leaking on to the ground or causing large amounts of white smoke to come out the exhaust, check the overflow bottle. Sometimes a hole will develop in the hose going to the overflow bottle. If this happens, the vacuum that is normally present once the coolant system cools off won't be there and it can't sucked the coolant back into the system from the bottle.

 

forgot to mention no smoke. when hot constantly runs at about 500 rpm its not an idle fault am running an ltx8 this has just happened today has been running fine for months untill this when started today compressions good new housings etc 6 months ago

 

My overflow bottle was dirty as hell, had some white oilly stuff in it due to my old n/a engine starting to go before I took it out. I've open'd the radiator cap while it was hot and shot a bunch of fluid into the overflow bottle. Now I have some shiny oily stuff in my radiator but my coolant is still green, could I have oil in my radiator due to sucking up some oily coolant from the resivour? Motor doesn't smoke and runs strong, hold a nice steady rev at 3k but due to a vac leak I haven't found yet it idles at 1200-1500. I have not been driving it just starting it in my driveway tring to fine the idle prob.

 

why does everybody think you should have oil in your water with blown coolant seals these are not piston engines that have an oil gallery sitting right next to a coolant passage under the headgasket. on rotary engines they are two separate circuits that dont even come close, all the coolant seals do is seal the coolant off from the combustion chamber the way i see it the only chance of having oil in your coolant is if it is automatic and the oil cooler in the radiator leaks into the coolant side of the radiator or a dowell o ring fails

 

I was referring to my o-rings falling due to mine being a JDM engine (which tend to sit for years a time).

 

i recently the best way to check is to drive the car and let it sit overnight. take the exhaust off the next day and turn the engine by hand. if coolant starts to run out of the exhaust, then you probably have a compromised seal.

until about 2 weeks ago, i would have sworn on the pressurized cooling system, but i've been trying to track down where i'm losing coolant for the better part of about 2 years now and i didn't find out until i was changing my clutch the other day and had to pull the exhaust to remove the exhaust shielding under the car.

when i started to turn the engine to torque down the clutch bolts, coolant started pouring out the exhaust ports. i thought it was the ******* Victoria Falls!

there were no leaks to be found. there was virtually no smoking, unless the morning was EXTREMELY cold. the plugs suggested a coolant leak, but it did not confirm anything. no ther signs of a leak other than having to add coolant every so often - went from about every 3 weeks to just about every 4 to 5 days.

 

forgot to mention that my car has great compression, too. it also idles fine at about 700 RPM - rock solid!