TheSamba.com :: View topic - Unsteady Idle Fluctuates Dies After Replacing Both Heads

Mon Oct 06, 2025 12:43 am

I just bought a 1989 Vanagon camper conversion by Trakka here in Australia. I had a Westfalia in the US but didn't bring it here. Wanted one so I bought this one that was leaking from both head gaskets.

Put new heads on it. New AMC heads. Replaced most of the coolant hoses. Used new head gaskets, water and air connecting gaskets, pushrod tube gaskets from Elring kit.

Put everything together and it won't idle. It would idle beforehand. I never drive the thing more than 200 yards but it would idle long enough for me to see that the heads were leaking at the gaskets. There wasnt any oil in the coolant or any coolant in the oil.

After reassembly I put everything back on like it was, and did not remove the distributor, throttle body, or anything like that. I did not adjust timing, not adjust air fuel, nothing adjusted.

It wouldnt idle under 1100 rpm or so. If it went down it would just stutter and die.

I readjusted the valves. No idle. I checked the sensor at the throttle and adjuted it to click as the throttle opened and went to WOT and it clicks just off throttle. Multimeter says .00 when on the outside of the sensor clicks. Inside the clicks it is infinity or UL. I am led to believe that is working.

I turn on the ignition to the run position and I can seel the idle control valve buzz for a few seconds and then go off. I believe this to be proper?

If I unplug the idle control valve it doesnt change. If I unplug the O2 sensor it doesn't change. The ground has .3 to .4 volts.

I put a multimeter on the Air Flow Meter and it appears to be smooth going from bottom to top. I unscrewed the board and shifted it to new carbon track area and tested again and it seems to be smooth and goes up in value the whole time without dropping off. I am using a digital multimeter.

It runs very rich. I tried opening up the large flathead screw at the throttlebody. I tried unscrewing the allen head on the top of the air flow meter. At times I can get i tto run smoothly and without smoking at 1000 RPM but after a couple of revs it will eventually go low idle and sputter and die.

I tried to adjust the timing but it doesnt seem to make much difference regardless of how well it was running. It runs the best at one setting (35 degrees) but is hard to start when set like this.

I checked for air leaks with a propane torch without it burning. Cant find anything.

Took the air intake boot off and looked for cracks. Cant find any air leaks on the brake hose or idle control valve connections.

I don't know what else to check other than the fuel pressure regulator. I didnt change or adjust anything. It is possible I did something or something happened or that maybe there was a leak at the manifold and replacing the gasket fixed it. I dont know. What should I check next?

Mon Oct 06, 2025 5:29 am

Buy cheap compression gauge and check the compression.
It is pretty common to have a compression leak on one or more cylinders after a job like this is done.

This would be because one or more valves isn't fully closing.
The compression test can tell you which valve(s) may need more adjustment.

Mark

Bntbrl wrote: I just bought a 1989 Vanagon camper conversion by Trakka here in Australia. I had a Westfalia in the US but didn't bring it here. Wanted one so I bought this one that was leaking from both head gaskets.

Put new heads on it. New AMC heads. Replaced most of the coolant hoses. Used new head gaskets, water and air connecting gaskets, pushrod tube gaskets from Elring kit.

Put everything together and it won't idle. It would idle beforehand. .....

Mon Oct 06, 2025 8:13 am

i have started using compressed air to set the valves in the WBX. the "1.5 turns" is not always correct and can lead to incorrect adjustment and burnt valves.

set the cylinder to TDC, remove the plug, use leak down tester hose and put about 20psi into the cylinder. adjust intake and exhaust valves until no air can be heard leaking and the pressure stays constant. this will give you a solid starting point, if any of the tappets are clacking, you will need to re-adjust once they are pumped up.

lapping the valves before installing the head is also recommended.

Mon Oct 06, 2025 8:28 am

It is common for the adjuster tips to get a flat spot pounded into them.
Then the adjuster can't evenly do the adjustment any more.
I'd hope that someone doing a head replacement would closely inspect the adjuster tips but my hopes for that kind of attention to detail are slowly fading.

Mark

Mon Oct 06, 2025 1:20 pm

I looked at the adjusting screw faces when putting them back on. They looked ok but I will pull off the rail and check them again.

Ill drag out the compressor and try adjusting them with the air method.

I questioned the valve adjustment so I did it again and got the same result. It will idle at about 1000 and then about 30 seconds later idle down to barely running. Once I put it in drive it will most often cut off within seconds.

I think this is where I was hanging up not sure what to look at next.

Thanks!