Well a couple days ago my truck started tapping like hell. I know somethings to look at and others not to. Well this one is being a pain in my butt. My 1st Gen with a 2.5 now sounds like it has a Cummings in it. I took it down to my friends garage where I've spent the last 2 days working on it and trying to figure out what's going on with it. Me and a friend thought it was the Pushrods and Lifters so last night I replaced both was in a garage working on it until 1am. Well during the tare down I discovered no Exhaust manifold gasket, no Head gasket, compression is at 190 in all the cylinders, I'm holding 75psi oil pressure and it still tapping, does anyone have any ideas or know what the issue is?

 

Does you truck have the cali emissions on it? If so it could be your smog pump going bad. When they go bad they will tap and rattle like the lifters are loose. If you dont have a good ear it will actually sound like the valves or lifters rattling. My truck has a 4 belt system on it and I just pulled the belt off that went to the smog pump and the noise stopped. I dont know what you setup is but if its like my 3.9 then I say try it cause it wont hurt anything to pull that belt off.

 

No there is no Smog Pump, it's running on a serpentine belt, and all that it runs is Crank pully, alt, water pump, AC, power steering, a small pulley, and the adjustment pulley. This truck is really getting on my last nerve and I really don't want to see it go to a scrapyard.

 

Oil pump may not be pullin oil good enough to get it up to the lifters and get everything lubricated good enough. If it dosnt have a exhaust manifold gasket then it may have a bad exhaust leak that sounds like that. Im not a mechanic but just tryin to help the best I can. Im stumped to. lol

 

It's not the Exhaust manifold gasket because I put a brand new gasket on last night it's a one piece gasket now, Felpro makes a one piece Exhaust and Intake Manifold gasket, so I know there is one on there now. I'm just really stumped, I also posted the same thing onto a Jeep Forum as well since it is a Jeep motor and they are all making comments on the non existent head gasket as if I'm nuts cause there wasn't one on there.

 

Oh I forgot to mention, the tapping noise only happens when the Motor is running. Heres a list of what was done so far. Since the compression was good I know it's not a valve or cylinder wall, the timing is dead on because I still have power and it will turn right over, I know I don't have a bad lifter or push rod since I replaced them all, the rocker arms are torqued down to 21 pounds, the head was torqued down to 110 pounds in the same order it says in the book starting at 22 pounds then moving up to 45 pounds then jumping it to 110 pounds except for the number 7 bolt which needed 100 pounds (according to the manual. Water pump is new, Alternator is new, I'm just really scratching my head on this one

 

PCV spring took a dump? That could cause a tapping as well.

 

No that was good. I'm gonna drop the oil pan tomorrow and see if I can see something from under it, I'm hoping I didn't blow a piston or something. To get another AMC I4 motor is not cheap it's not like a 350 or 305 or even a 318 they made this motor for a couple of years. AMC took the I6 block and modified it by cutting 2 cylinders off and turning it into a 4 cylinder. Around my house cheapest motor I could find just by using the Google, Junkyarddog.com and mypartshop.com was like $600. I could by a Honda for the price of a motor LMAO! But I'd rather own a Mopar, I like them alot more then Fix Or Repair Dailys, Hondas or BEND EM' OVER RANGE ROVER!

 

You could always use a screw driver and put it to your ear and start probing around for the location of the tick. Should help you to determine if its external or internal. A friend of mine had an I4 in his Wrangler and he had a tick that we determined was a bad valve. Do you notice any colored smoke coming from the exhaust? And pull the plugs and see what color they are. That will help to tell what each engine cylinder is doing.

 

No smoke coming from it, no smoke coming from anywhere that's the thing. All the plugs are the same color alittle tan from use but none fouled. Tried the screwdriver, sounded like it was either the valves or the lifters hence why I changed them. I don't know I'm gonna drop the oil pan tomorrow and hope like hell that it's something simple and not a piston, a bearing or something like that cause I don't really wanna do a rebuild.