So I bought a cheap 97 with 160K miles a couple months back for a project/extra vehicle/off roader/parts truck/whatever..... It started and ran, but obviously had internal engine issues from the PO telling me it had overheating issues and the oil looked like a chocolate milkshake on the dipstick.

Trailered it home and took the heads off. An obvious blown HG between the water port and rear left cylinder #7 - and that piston head was clean of carbon. Cylinder #5 also had very little carbon buildup on the piston head compared to the other six - but at the time I didn't pay much attention to it. Probably should have though.

Ordered HG set from AB and had the heads checked/milled/cleaned. Put it all back together and it fired up like a champ. Motor runs smooth and strong, no ticks, no exhaust or coolant leaks. I bled all the Brakes and it drives and stops good. I had some trouble getting the cooling system bled at first, but eventually got good heat and normal running steady temps around 183 on the ultra gauge.

HOWEVER.....After a cold start, once it hits 130 degrees on the UG, out comes the white exhaust. The smoke doesn't smell sweet to me like burning antifreeze, but maybe I'm not used to dex-cool smell...? After the engine warms up, it gets the bubbles in the expansion tank. I rented a block tester from o'o'o'reilleys and the coolant tested positive for exhaust gases three times (...that reminds me, I need to return it for my deposit). All the cylinders pressure tested OK at 180-190 ft/lb, but that f'n#5 spark plug was wet with what appears to be coolant. The #7 plug looks fine. Oil still looks perfect. No oil in coolant. Haven't lost any measurable amount of coolant in the short time I've ran it, yet. No codes on the ultra guage so far.

I've only put a couple of hours on the engine, but I'm pretty sure I have a parts truck now. Does everyone agree? Assuming heads and gaskets were repaired/installed correctly it has to be a bad block? A crack or slipped liner? Any other possibilities?

Any point in putting stop leak in the engine to try and get some miles out of it? Should I pull it apart again and try to diagnose the problem?

I have a 98 daily driver and my brother has a 95, so I figure we needed a parts truck anyway.

 

Sounds like the block. There is no coolant passage at that cylinder so any coolant in the cylinder would be coming through the wall. You can try a sealer because at this point what do you have to lose?

 

I have a 1998 (now parts vehicle) with exactly the same problem - let me know how the sealant works out. I was going to give it shot at some point just to see. The engine only hast about 4500 miles on a rebuild (not just head).

 

How long have you been running it since doing the headgaskets? Mine had terrible white smoke for the first few runs and then it cleared up. The smoke was so bad I thought I botched the headgaskets.

 

Have had it running around 3-4 hours, mostly idling in the garage with pipe running the exhaust outside. Have driven it 4 or 5 miles total so far. Am waiting for warmer weather to work on it outside and inhale less CO from slightly leaky muffler.

I was hoping it was just moisture or residue in the exhaust system at first. It sat for a few months without running, and the nasty oil could have gunked up the system. Some more running/driving is in order when I get some time. Overheating or obvious loss of coolant would be a bad sign.

 

Did you exchange the coolant or just drain it down and then add it back into the radiator?

Did you happen to notice a dab of paint in the lifter valley by chance? What color was it?

Your engine isn't *bad* until I say it is.......

 

Ok I take it back, it isn't bad..... yet. I'd love to be proved wrong on this one.

I didn't re-use any of the coolant. It was weak anyway, so I drained the old stuff put in some full strength in case it got below freezing before I got working on it. I didn't flush the coolant system at all, just siphoned most of what was in the radiator, did the HGs, and added new.

I don't reacall any dabs of paint in the valley. I wiped down most of slimy oil/coolant mixture from the valley and lifters and can't remember any dabs.

 

Where are you located?