sporeprince Posted July 17, 2021 Report Share Posted July 17, 2021 hi everyone! i purchased a 1984 4x4 5spd about a year ago now. it ran great at first, and the guy i bought it from rebuilt the engine and said it was a daily driver, under 100,000 original miles, body in amazing shape. however (classic sob story) within a few weeks of buying it the engine started to tap neither i nor my mechanic could figure it out. turns out the timing chain guide was broken and the chain itself was eating away at the guide until it was a stub. eventually the third cylinder completely gave out and lost all compression. i'm very very new to all car stuff but i'm (slowly) working on this truck with my dad, who has a lot more experience. we've decided to just open up the head and see if we can diagnose, if anything looks obviously wrong. what i'm wondering is: what do you think i should look for? deformed valves, scratched cylinder wall, cracked block? did the timing just get really off and that's why the third cylinder went out? also, any tips for opening up the engine: mistakes i shouldn't make, things to make life easier? thank you!!! i towed the truck from louisiana to vermont so i am very committed to getting it to work again. attached is a picture of my baby when she still ran 🙂 1 Quote Link to comment
bottomwatcher Posted July 17, 2021 Report Share Posted July 17, 2021 That will be rare in Vermont. I dragged mine from Florida to Maine. Can't get gas without someone commenting on it. Mostly they all rusted away. Don't drive it when they salt the roads they are very prone to rust on another note make sure you wedge the chain before pulling the head. These are all prone to headgasket failure. Notice any steam from exhaust or milkshake engine oil when you lost compression? Quote Link to comment
captain720 Posted July 17, 2021 Report Share Posted July 17, 2021 I would pull the head and do a new osk chain, it's not that much more work and your "baby" is with it 3 Quote Link to comment
datzenmike Posted July 17, 2021 Report Share Posted July 17, 2021 Looks like '80-'82 front fenders, hood looks right for an '84 as they interchange and so do doors. Fenders were replaced. Fender badge is pre '83. Grill badge would say NISSAN and '83 -'84 would also have 4WD and 4X4 from '85 on. Compression loss could also be an intake or exhaust valve rocker lash that is too tight and the valve can't close properly. All valve lash are 0.012 hot. Really nice truck! 2 Quote Link to comment
Lockleaf Posted July 19, 2021 Report Share Posted July 19, 2021 ghetto Leak down test will tell you where the loss of compression is. Turn engine so you know the dead cylinder valves are all closed. remove air filter lid and oil cap and spark plugs from other cylinders. Inject air in to cylinder and listen. If you hear hissing through oil cap, then your rings are bad. If through Intake, then intake valve is not sealing. If through exhaust , then exhaust valve not sealing. If air comes out of next cylinder, you have a head gasket failure. If you hear air everywhere, then you haven't really learned anything, but you haven't lost anything. But it might tell you if your head is what you need to work about. 1 Quote Link to comment
620slodat Posted July 20, 2021 Report Share Posted July 20, 2021 That is the first time I've heard that ghetto leak down test. I like it since it doesn't cost anything to try it. Don 1 Quote Link to comment
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