recently picked up a 2005 g35 coupe 6mt. Test drive the car approx 30 miles mixed highway and city and everything seemed fine but then as I was pulling into a parking lot it overheated and started spewing coolant. Filled it up and limped it home. I flushed and refilled the radiator and spent the next few days trying to bleed air from the system to no avail. This was my first indication something was wrong. Secondly my coolant reservior smells like gas. Not good. Lastly I have no coolant in oil and no oil in coolant

Heres my diagnostic completed so far:

1. Got a block tester to detect exhaust fumes in the coolant. Even though the reservior smelled like gas it never failed this test. Anyone know why it would do that?

2. Picked up a coolant system pressure tester. Pumped the system to 23 psi as recommended by the service manual. After about 30 mins it had dropped to 22 psi. No visible signs of an external leak. Is 1 psi too significant a drop in 30 mins?

3. Bled off the air pressure and reinstalled the coolant pressure tester again and started the car. After a minute it was reading about 5 psi at idle and temp was about 30% normal operating temp. Punched it to about 3k RPMs and each time the pressure jumped a few psi. Is this abnormal?

4. Pulled the spark plugs. All were white but none wet with exception of the rear drivers side plug being covered in oil. I'm assuming from a bad valve cover gasket.

5. Ran a compression test and these were my results from front of engine to rear:

Driver side: 170,180,175
Passenger side: 158,180,155

Seems like I have first and last cylinder on passenger side low, but still above minimum but not within 10 psi of others.


With all this info what does everyone think? Obviously I haveacouple cylinders with low compression but it's not awful. Also, low compression typically shows with two cylinders next to one another,but not in my case. This makes me worried I have a cracked or warped block or head and not just a head gasket. Would I be better off replacing the whole engine instead of wasting time and money tearing into the heads?

 

Return it to seller and get your money back

Telcoman

 

Unfortunately not an option. Downside of buying a 12 year old car on Craigslist I guess.

 

Is the car still over heating?

My previous engine seriously overheated, gaskets gone and both the heads and deck surfaces were warped. I manually planed them and put new gaskets back and it drove fine but spun a bearing about 500 miles later. Most likely because sanded material wasn't thoroughly removed. Also, as I planed my heads and decks the timing chain wouldn't match up the OEM markers so my timing was slightly off. I couldn't tell but I did get an engine light and code for over advanced timing.

In the end I decided to drop in a used engine instead of further mess around with the previous engine. I picked one up with "100,000 miles" for $800, dropped it in and all seemed fine. If you go this route make sure you get 30 day guarantee or something with it. Still a gamble but if you can do the work yourself then the cost of an engine to is not too bad.

But, if your car is NOT over heating anymore and NOT using any water and there are no symptoms of problems, just keep driving. But do figure out why your car overheated in the first place. When I bought mine there was a hose that had burst. Replaced this hose thinking that was the cause but it wasn't, so it then overheated again. The root cause was the rad fans not coming on, which then caused the hose to blow. Even after I sorted the heads my car overheated but it wasn't severe, only then did I figure out the fans were the problem.

 

Did you try putting oil in the low compression cylinders? If the PSI jumps up it usually means your piston rings need replacing.

You can also try doing a leak down test.

 

I found a massive tear in the intake elbow when I removed the engine cover. I know this will cause a very leancondition and is the source of my very white and crusty spark plugs. Would this cause enough heat in the combustion chamber to overheat? My plan today is to get this fixed then refill and thoroughly bleed the colling system with a spill free funnel. Then I'm going to drive it and monitor coolant levels. I know driving a car with a suspected head issue isn't the best idea but my case is not at all what I would consider severe through my tests and I think further driving and monitoring would be the only way to really know what's up.

What is still bothering me is the cooling system pressure testing. Is 1psi loss in 30 mins enough to show anything? Is the 1-5psi reading on a cold engine alarming? What about the 2-3 psi jump when Reving the engine to 3-4K RPMs (fans not on/thermostat prob not open)?

 

Running car from fully cold at idle right now with spill free funnel in place. No indication of bubbles in funnel with closed thermostat. Still no heat from vents at idle. Once the car got up to operating temp and the fans kicked on the coolant started to overflow the funnel and become pretty turbulent. Couldn't tell if this was from bubbles or not. Is this normal?

Also I must add this: Im running almost completely with distilled water. Didn't want to mix 50/50 because I knew I'd be in for a lot of diagnostic and mess. Is this causing my boiling point to be too low?

 

Drove the car for about 20 mins and it overheated again. The coolant reservoir was almost completely full and there were sign of overflow (water near the top hole). What causes that?

 

Tried using spill free funnel and having same problem as this guy


Allso my lower hose is now cold. Thermostat stuck shut?

 

Tested the thermostat and it checked out just fine through multiple heating cycles up to 180F. Am I just another person with a blown HG who is in denial and trying to blame everything else?

Still can't get heat at idle in the car. When I removed the rad cap from the last overheat a bunch of air came out. Am I just continually fighting air pockets or is something else introducing air?

 

Well these cars are notoriously hard to bleed air from coolant system from all I've read. Some folks put the front up on ramps to help get the air pockets to move. Try searching the forum for threads on that.

 

Update from today:

Drained entire system including removing the plug in the drivers side of the block (couldn't get to the others). Refilled the system and tried again to bleed the system. I am continually battling turbulent coolant in the funnel and my lower hose is totally cold. Seems like my thermostat won't open with the funnel, but once I put the cap on and pressurize the system it does. any ideas? It also almost overflowed the reservoir again today during a 15 minute drive.

 

Might be a broken impeller on the water pump, thermostat is opening but it's not cycling water, finally it hits close to boiling point and starts overflowing at the radiator cap, also why it seems impossible to bleed out air bubbles.

Unfortunately it's a lot of disassembly to check the water pump...

 

Another update:

I allowed the car to fully cool with the funnel installed and topped off with fluid overnight. It sucked up about 1/2 of the coolant in the funnel while cooling. After this I finally got past the turbulent coolant issue in the funnel like the video I posted. I ran the car for about a half hour yesterday with the funnel in it. Got the car up to operating temp and was able to accelerate up to 3K RPM's and hold without the funnel boiling over. Heat in the cabin got hotter at idle the more times that I held the RPMs up and expelled bubbles. I think I had a large air pocket in the lower radiator hose causing my t stat to not open. All hoses are now hot when car is running with funnel.

Fingers crossed but hopefully I got very lucky and it is just air bubbles in the system. I was still getting some small bubbles after cycling it at elevated RPMs at the end of 1/2 hour. Let the car cool overnight and will be attempting to bleed again this evening. I'll post results.

I haven't totally ruled out the water pump as I have some rattling and whining noises coming from the front of the engine while running. This could be water pump bearings, or it could be any of the other pullies on the main belt. I have an '05 so disassembly only requires removing the cover plate to inspect so I may attempt that soon.

 

Tried bleeding the system again yesterday evening. No bubbles in coolant upon startup or at idle. Bubbles still present after the car heats up, thermostat open, fans on, and I hold it at 3K RPM's for 10-20 seconds. I get medium to small size bubbles for about 30-45 seconds after I let off the gas.

Is it normal to still have bubbles after 2 bleed procedures with a spill free funnel and running for 30 mins between idle and 5 rounds of holding at 3K RPM for 10 sec? I know these cars are a PITA to bleed, but this seems ridiculous.

Is it possible I have a small head gasket leak or cracked head that doesn't open up until the engine really heats up? No bubbles upon startup or at normal idle speed, only when I rev to 3-4K and hold for a while to really get the engine heat up. Maybe it's time to throw the cooling system pressure tester on a hot engine and pump it up to see if it bleeds down quicker.