Originally Posted by DFlintstone

Thanks again for great info ^. I guess used, concave lifters riding on a nice flat new cam is a bad idea. The other way around, not so bad.

And it will "cycle" like that? Do you have a gauge or a light for your oil pressure?

Originally Posted by Big D Squared

I've used just the regular castrol high mileage 30 w 50

Originally Posted by Big D Squared

Yes it will cycle like that and yes I have a gage

Originally Posted by DFlintstone

Not that I can say I've ever really just sat and listened to a tick, but that sounds unusual. Of course I'm curious if the pressure fluctuates with the sound.

If it's cycling, something is causing that, and I can't think of many options. That, pressure, and the temp. Thermostat sticking? Pops open when it gets supper hot, then a rush of cold closes it again? OK, a stretch but I'd watch the gauges once to see if they are doing anything.

Originally Posted by 5-90

Remove valve cover
Remove rocker arms
Remove cylinder head
Remove lifters
Install new lifters
Reinstall cylinder head
Reinstall rocker arms
Reinstall valve cover.

Sadly, the "Modern Era" AMC six never got a side access plate inbuilt - which is something I consider silly. Thus, the head must be removed to access the lifters for service.

How sure are you it's a lifter tap - have you undertaken any diagnosis to isolate or identify the noise? It never hurts to be sure - and a mechanic's stethoscope is both a cheap tool and a very useful tool!

If it does seem to be a tappet knock, I'd suggest flushing your oil first - most tappet knocks are caused by a buildup of sludge or varnish in the tappets, which interferes with the free action of the plunger. Ergo, something detergent enough to break the crud loose is helpful. Ideas that have worked for me before:

- Change the oil. Replace one quart of engine oil with one quart of Marvel Mystery Oil - it's good stuff! Run normally, drain while hot. Repeat PRN.

- Change the oil. Replace 1-2 quarts of engine oil with a like amount of automatic transmission fluid (Type F is more detergent than Dexron/Mercon, and will be more aggressive...) and run fairly hard for 500-1,000 miles and drain while hot. I don't suggest doing this twice on the run - automatic transmission fluid can be antagonistic to engine seals. (FYI - Type F also makes a good ersatz hand cleaner. Use the Type F to get the crud off, then use regular soap to get the Type F off.)

- Use a good engine flush - Berryman's B-12 Chemtool works, and I've heard good results from Seafoam and I think Lucas makes something that works fairly well - and follow the instructions on the can. (I usually do this sort of thing as a "maintenance flush" - I've noted the previous two methods tend to be more aggressive.)

NB: Whether or not you've got sludge or varnish buildup that's causing your tappet knock, you may have a leak "appear" after the flush. This would be because you've had a seal that was about to go out anyhow, but it had a buildup of sludge that helped to keep is sealed. Flushing the sludge out often brings these incipient leads to light - it merely accelerates notice of a failed/failing seal, it doesn't cause seal failure in and of itself. This is also common when switching to synthetic oils - which has started the "synthetics cause leaks" myth.

Considering the difficulty in replacing the liftes on the 6-242, I'd try a detergent first. For best effect, you should drain your oil as hot as you can stand it - it will carry more crud out that way.

Originally Posted by Bookworm94

knocking
I have a lifter knocking too, or I suspect it's a lifter I should say. How can I know for sure without openings anything up? Also is it safe to drive? I just bought it and they did a overhaul on it but I don't know what all was done too it. It's a 2000 grand cherokee laredo, it didn't have a tick before I drove 1100 miles today but now it has a seriously bad tick.

Originally Posted by superj

It's not an exhaust leak on the grand Cherokee, right?

Originally Posted by cruiser54

All the time or just after cold start?

Originally Posted by cruiser54

You may have a bent pushrod.