Botched Head Gasket Job - Help ??

[mrdance123]

Despite the coolant loss and steam venting out the overflow tube, the engine ran fine and idled normally at 500rpm. After head gasket replacement and reassembly, it will not idle at all. I have to turn the idle screw up 2+turns and it runs only if kept about 1500rpm. Try lowering idle gradually, but it suddenly and quickly dies with the smallest adjustment < about 1500 rpm. I tried a working spare carb, same problem. Verified all hoses are correct comparing to the service diagrams, and my other running T4. Acts like vaccum leak, but sure can't find it. I know about the line under the air cleaner that must be attached, or closed off when running without the air cleaner on.

[marlinh]

Is the timing belt on correct? Distributor timing?

[lannvouivre]

Did you try using carb cleaner to find the leak? These cars are set up pretty nicely for using carb cleaner, since the only spot you can't easily spray is the underside of the intake manifold. Just so you know, some rubber caps sold for blocking vacuum ports get destroyed by carb cleaner.

[mrdance123]

Timing belt (cam timing) is right on, the cam sprocket hole lines up with top notch mark when #1 is at TDC.
Distributor timing: close enough. It sounds good and responsive with rpm's on it. Normally, when timing maladjusted it only lacks power if too retarded, pings if too advanced, or it won't start, so is not the problem. To pass emissions I badly mistime (retard) the timing (for the test only) so it barely runs, and it passes despite having a bad catalytic. The idle speed screw and distributor timing can be adjusted to compensate for each other...to a point.. to get good idle speed... Never seen timing cause problem i'm having- the sudden quick shutdown trying to slow down my 1500 plus rpm idle, turning down idle speed screw slowly, just a bit - dies like someone turned off the key. I've been off a tooth or two with the distributor gear sprocket on the cam, it never acted this way, it simply won't start and might backfire. I've done 4 head gaskets over the years on different T4's , never had this problem before. STUMPED !!

[xirdneh]

sounds like a carb related problem to me
when you swapped carbs did you use same aft solenoid?
the aft solenoid not working?

[dlb]

big vacuum leak?

[Petros]

not likely a bad head gasket would cause that (verify with a compression check). Sounds like something in the carb/intake/emissions system got disturbed or broken. verify that TVSV is not broken or cracks, it iwll act like a big vacuum leak.

if the head gasket was not sealing, it would cause it to run slow or stall out, not idle too high. look for sourse of vac leaks, verify the throttle linkage is adjust correctly and not hanging up, etc.