Exhaust gas in the cooling system. 97 GTI

[OVRAT]

Have a 97 GTI (717) that has exhaust gas coming out of the cooling ports. Pulled all three cooling hoses off of the head and there seems to be more gas coming out of the discharge port vs. the inlet and port to the exhaust pipe.
Runs fine in the driveway on the hose. Rear deck water stream looks normal. When it is in the water, the rear deck stream is intermittent and shoots several feet. Water is hot to the touch.
I thought I might be having carb issues with occasional hard / no starts out on the water. I now suspect that I have an O ring in the top end that is barely leaking, loosing compression, is the source of my hard / no starts and exhaust gas in the cooling system. I haven’t checked the cylinder compression yet. Anybody seen this before? Any thoughts?
Thanks

 

[JPX]

I'd check the condition of the gasket to the exhaust pipe from the exhaust manifold. This is a crucial link where water and exhaust can mix (other than the much more sensitive area of the head).

Compression test. Must do compression test.

 

[derek]

the exhaust pipe itself can have a hole rotted inside it. difficult to test without changing the exhaust.

 

[OVRAT]

Compression check

Checked the compression today. Cold the front cylinder was 100 psi and rear was 90 psi. Hooked up the hose and tried to warm it up. Both cylinders read 90 psi after 8 minutes of running. One thing that I had noticed was that the front right (viewed from rear) cylinder block was noticeably warmer than anywhere else. May have been wasted energy. Shop manual indicates that you can’t test the compression individually due to the shared intake manifold. How bad is the 90 psi reading?
I had already checked the gasket between the exhaust manifold and the tuned pipe.

 

[OVRAT]

Waste deep

Decided to jump in and removed top cover and head. Definitely had issues with the rubber around the top of both cylinders. Non-existent in some places. Rubber on top of the head didn’t look too bad. The head looks like it has had some heat from the blow by. Outside O ring grove is missing a 1” lip from corrosion on the inside. Thinking I should replace the head. Great news is that the cylinder bores show no scaring. :cheers: Debating whether I should remove cylinders for clean up. Are the bolt thread bores blind? They appear to be, just don’t know if it is corrosion / sealant in the bottom. I would like to run a tap through those thread bores. Looks like I can remove the cylinders without disturbing the intake. Any words of wisdom? I apologize for being a newbe to the site and asking where is the best place to order parts from. There has to be a better place than the local dealers.
Thanks
OVRAT