Tap/light knock

[RestorationRides]

All engines are going to make that hissing sound as you cycle through the compression stroke on each cylinder. Take out all of the spark plugs first and then run compression checks to get a sense of the relative health of each and all of the cylinders. You're looking for a significant difference in the pressure on 1 (or more) cylinder compared to the rest of them. You also need a minimum average pressure on all of the cylinders for the engine to start well and run efficiently. If the pressure is down significantly on any of the cylinders , you can next run a leakdown test and see where the pressure is escaping to...

RR

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[Elheffa]

Had a compression test done by a shop and test came back good with a cylinders within 4psi of each other. i have never opened up the motor and turned it to inspect pistons so thought it weird to get that hissing. also while under car i took a torque wrench down all the cap bolts. come to find out 3 of the bolts were loose at the rear of the motor not sure why as havent messed with them at all. on start up my super loud tap has quiteded down a lot and is now fairly quiet will be replaceing lifters here soon

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[RestorationRides]

4 psi variance is good. What is the average pressure...?

Good Job on finding the loose caps. Rods or mains? How loose?

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[Elheffa]

Psi was as followed

6- 147
5- 146
4- 149
3- 148
2- 146
1- 147

The end caps i had to put a 1/4 turn to get to 80lbs toque on 3 of the bolts. 2 were on same cap so backed them all off of each cap after they turned. then went 40 each 70 each then 80 each as they called for. Might do a new compression test to see if it changed since bolts were loose when i did original test. Maybe got inaccurate reading but never hurts to double check (except the wallet sting of $80 but i can live with that to make sure everything good)

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[Bird5]

I know you realize that a manifold leak will make a loud pecking noise at start up and subside some after the engine heats up.
Another quick way to check for ring wear is to remove oil cap while engine is running. I once blew my hat off doing this.....bad ring.

 

[Elheffa]

I run the jeep with oil cap off frequently no excceve pressure in head

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[RestorationRides]

Still not clear to me. Are we talking rod caps or main bearings caps...

Don't pay some mechanic 80 bucks to do your compression check. Just go down to Harbor Freight pick up a guage for probably less than 50. Use the 20% off coupon. And that's an item that's always on sale. You can pick up a leak down tester there too, but I don't think you really need it. All your pressures are good and probably pretty close to the original compression ratio of that particular engine. I'm going to try to look it up now

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[Elheffa]

Currently working 7 days a week so it 80 or it dont get done untill after spring break plus its the macanic my grandmother has been going to for 30 years plus they pick it up from my work and drop it off same day for the 80 so works in a pinch. And the caps were the crank bearing caps qq

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