LT5 technical problem

[8upZR1]

I have tried starting it without the oil filler cap and it makes no difference. The engine turns over nice and all sounds are normal, even when it ran it sounded good. After it did not start with the valve cover put back on I checked the compression on #6 and it was 0. I have never heard of a problem that causes varying compression but it obviously exists. The lifters are the originals. After the head gasket blew I removed them and put them in a plastic bag full of oil. Never touched them. The 3rd time I took the engine apart I noticed they were locked in the fully extended position. Through the use of extreme force I managed to unlock them. Afterwards they seemed to be in good shape. They rotate and slide in the bores beautifully.

When I have a minute I will remove the cam cover again and re-measure the clearance between the lifter and the cam. If all else fails I will instal a new set of lifters.

[petefias]

Did you check the compression in 2, 4, and 8? Are they good? If 6 has good compression without the covers the answer is in the valvetrain.

My guess is that the camshaft is broken, I know it doesn't make much sense. Maybe with the valve cover installed there is too much drag on the cam and won't turn, with the cover off it just turns enough to run.

Another possibility is what was suggested before: the lifters/pushers are "overextended". With the cover off the cam lifts off enough to not matter.

Good luck and let us know...

[jonszr1]

Here is a young man that might be able to help you out. He is without a doubt one of the most knowledgeable Lt-5 guys around. plus he is one of the most kind and helpfull people I've ever met. Run your problem by him. tell him I sent you . Opps I'm brad his name Corey Henderson ph# 210 867-6286. He owns hpt in New braunfells tex . I just know he can figure this out . Good luck.

[8upZR1]

Thankyou for the phone #. I will give him a call today. Initially I only checked compression in #6 cause that was the cylinder that happened to be on the power stroke and therefore both cams were riding on the base circle. I had a theory that the valves were open on the base circle but that was just not the case. I only checked the compression of the other cylinders after the motor failed to start with the valvecover removed. The cams are good, and correctly installed (L,R,I,E). The cams are held perfectly in place by the small caps that go on before the valvecover. There is no play. If the caps were pressing down on the cams they probably would not turn easily, but mine do. I thought the lifters were over extended, however, they are completely empty of all oil and can be compressed slightly by hand. When I had the valvecover off I pushed against the lifter and this created a measurable gap between the cam and lifter. This tells me that the valves are completely seated, as the valvespring would be pushing against the lifter and the gap would be closed if the valve was not on the seat. I checked the valve job seal by pouring water into the intake and exhaust ports to CC them. The ports hold water without any leakage. Also I believe that this is mostly intake related as I was seeing combustion occur inside the injector housing ports when I tried to start the motor without the plenum, and minimal flow coming from the exhaust.

I just don't know anymore. I will call this Corey fellow, perhaps he has experienced this. I hate the LT5, and everyone who owns a working example. F you all.