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Tue Mar 31, 2015 8:53 am

1988 Vanagon GL original 2.1 block, 175,000 miles. Overheated last Fall, melted thermostat housing, broken engine bay bleeder loop connector results in stuck valve, bent rod and tube passenger side. Still started and ran on 3 cylinders. Repair consisted, new passenger side AMC head, rod, tube and gasket kit installed, new gasket kit on the other side. New cooling system except for maybe half the hoses.
Result, bled with Libby Bong, starts right up, drives at 2000 rpm all day with needle in then middle. Increase the rpm to 3000+ needle swings to 7/8, blinks. Pull over, pressure tank and overflow tank are moaning in pain. If I go down the combustion gases path, that means I did wrong on the drivers side head, maybe that head had an internal crack that I could not see. I replaced the green o-ring as part of the kit however I did not use any vaseline when installing (heard about that yesterday). 2 questions, why run all day at 2000 but not 3000 (existing cooling is adequate for the 2G bu not 3G?) What next? which side? Both? check for what?

Tue Mar 31, 2015 8:33 pm

Was your hd torking pattern correct & done in steps? ? What was final tq amt? It's a std comp leak, i would do a re-tq of heads, do easy (pass) side 1st, test drive, then other side. Did u use new sealing rings between hd & cyl? One of mine when bought acted this way, keep under 55 &ok, drove it in slo mode until weather improved and resealed pass side, got lucky 1st try.

Wed Apr 01, 2015 7:33 pm

Followed the green book, 3 steps of torquing, I read one should use the needle indicator torque bar, tool store only had the handle twist gauge/click type, bought the gasket kit and installed all the associated parts including the sealing rings you mentioned (kept popping out during install then used some vaseline to stick them in place.

Wed Apr 01, 2015 7:48 pm

There is no easy answer for diagnosing your problem. Doing the head nut torque again is about all there is to try. Did you make sure the head nuts were clean inside before you put them in? Borrow a beam type wrench and give it a shot.

Mark

Thu Apr 02, 2015 4:39 am

Clean threads on BOTH the studs & the nuts, crap inside, deep, & they screw on fully , easily with fiingers.

Thu Apr 02, 2015 5:08 am

Well....

Pull the rocker arms on the suspect side, or at least loosen them so that the valves will NOT open. but I'd remove them to avoid bent pushrods.....

Get a hose that screws into the spark plug hole and pressurize the cylinder with about 150lbs of compressed air.

DO THIS WHILE THE ENGINE IS COLD, best to have tested piston at full down travel to avoid engine rotation surprises!

Watch the coolant level in the tank..... does it rise and then begin to bubble?

If so, pull the heads and reseal or replace as inspection dictates.

Dave

Thu Apr 02, 2015 6:32 am

Here are a couple of shots of the head when I removed it about a month ago. All valves were equal except for one which was maybe a 1/16-1/32 up. One side has your typical crack between valves (how deep? potential cause of combustion gases?), you might also notice the sealing ring has a bit of a wow in the photo (squished?). The new one was properly installed. Valve is pretty white, cause? studs were cleaned, anti seized, and sealant placed on the head bolts prior to install.

I can smell removing/replacing the head, but prior to I will re torque the bolts.

Thu Apr 02, 2015 1:53 pm

many of the FLAPS will loan you a block tester (you buy the test fluid) for checking hydro carbons in the cooling system. Seems like you could confirm this prior to working on the heads again. You said you replaced half the cooling system, maybe the problem is there, like a bad blue expansion cap, or misrouted hose or kinked hose. Just confirm hydro carbons first.

Also, a leak down test should tell you if the trouble is coming from the combustion side of things... but the block tester is so much simpler.