Question on compression numbers

[leo5150]

just wondering what the ranges are for the 6.2l as far as what psi is considered poor, fair, good, and excellent. I'm going to buy a compression tester tomorrow and test my compression. I have a engine that likes to crank a lot before starting, about 4 to 9 sec if she has not sat for a while. if she sat for a day or two then all bets are off sometimes 3 to 5 glow plug cycles with 10 to 15 sec start times. I have added the bypass for the glow plug system

[john8662]

Your problem doesn't sound like compression. Sounds like you've got an air leak and fuel is returning to the tank after shutdown, causing a very hard start. Resolve ANY fuel leaks on the engine first.

Compression is in the range of 380-410. The important thing is good compression and that they are close to one another.

Taken with a warm engine, fast cranking starter and great batteries, counting the puffs 6 times, the 6th time is your number.

[leo5150]

So you're saying I should probably first replace all fuel lines and Clean and/or replace all the cables to the battery/starter correct? That should probably be done anyhow considering I do not have a clue how old the fuel lines are and the cables are probably just as old. Does anyone have an idea of what size and how many feet of fuel line I would need?

[john8662]

Just replace the rubber lines. They're gonna be 3/8 and 1/4, get fuel injection hose if you can get it, much better stuff, and a lot of good worm gear hose clamps to replace some of what you got.

Probably pickup about 6 foot of each if you're doing all the rubber line connections.

Have you seen the post the top of the 6.2L forum about air in fuel? Make yourself a cap test for leaks.

J

[leo5150]

Well I picked up the compression tester from HF. Warmed up the engine, removed the glow plugs, installed the Schrader valve and cylinder one and got 400 psi!!! Then I installed on cylinder three, I could not get the compression tester to fit the Schrader valve. Need some sort of extension for that. Decided to test on five, 388 psi, and six got 390psi. Move to cylinder seven cannot fit the Schrader valve around that one either, manifold itself is in the way along with two, four and eight. Any advice on getting this done with out tearing apart the engine to do it?
or maybe an extension?

[leo5150]

was inspecting the fuel lines and the one going to the IP was looking iffy. then I noticed that 2 of the hard lines going to the injectors had a "wetness" to them. sprayed them with drake clean and will look after a drive. I also looked at the IP witness marks and noticed that they were inline so I advanced the IP a 1/4". I think this was a little too much because the drive to a friends house the valves sounded like they were raddling to much. but she sure did start nice.

[RAYMONDK]

When they get lots of miles on them the timing chain stretches and the factory timing mark becomes no good. Also the factory timing is late for emissions purposes. I set mine with the engine running hot for the quietest idle. Runs great, starts before you can let go of the key and gets 25 MPG.