• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Fixing bad lifters??


NAXJA Forum User
Have been having an odd sound from the valve area of the engine that coinsides with a missing in the idle.
I assume that it is a bad lifter?
If so, anyone have ideas as to how to replace them?
Can using "seafoam" be a cause to the problem?
might be sticky valves. Not good either way since it can wear the cam lobes.

try a few 3000+ rpm blasts on the highway. The valves are designed to rotate above that RPM. The idea is to burn off carbon deposits and get the valves to rotate in their guides.
If there's no improvement after flogging the engine, it's likely there's something awry in the valve train.

seafoam in the crankcase oil can loosen junk and make matters worse. Its safer for a 2-cycle outboard, without valves/lifters.
better to use synthetic oil, and break down the sludge slowly. across several oil changes.
Last edited:
A blast, as in hard acceleration, in gear, and with plenty of open road in front of you.

If a valve or lifter gets stuck, the cam lobe may wear out. The engine will miss, have higher emissions, and may burn extra fuel.
If there's no improvement after flogging the engine,
I wouldnt flog my engine, it hath done nothing deserving this punishment.
seafoam in the crankcase oil can loosen junk and make matters worse.
Im an example of this. After putting seafoam in the crankcase oil, it loosened up so much carbon sludge, the oil sump pickup got so clogged the oil pressure would drop to nil after a couple hundered yards. Had to drop the oil pan and THATS not fun. Ill not do that again unless its to remove eater from the engine after a submersion or some such thing. BUT it DID break the carbon up!!!
I regularly blast to 4750, and cruise 2500-3000

I've also accidentally gone to 7000 three times, I chucked my floor mats soon after!
No more sticky lifter after that!
If you want to clean them a bit more gently replace two or three quarts of oil with a full synthetic and drive it, gradually it will clean the engine up. I have never had any of my engines running full syn ever get any crap in them.
Mystery Oil is your friend. Used it many times to decrease lifter noise.
Right before your next oil change put a quart or two in your oil and drive around some.
Also, while hand throttling the engine, add some through a vacuum line into your intake. A few high RPM's here will help.
This may not completely fix your problem but I guarantee if you do both it will help.
Per this post I tried the Marvel Mystery Oil today. I stopped by the auto parts store and got Oil, Marvel's, and a Puralator filter. Got it changed, drove it till it got good and warmed up, then did a few blasts down the highway and back. I can already hear a major difference in top end noise. It's much quieter.

I got this XJ about 6 weeks ago and knew it had some issues. This was the last thing that really needed to be taken care of and hopefully the Marvel's did it.

Can't say whether this is the end all/be all, but it certainly seems to be working.
MMO is basically mineral spirits (paint thinner), a little naptha, and some chlorinated hydrocarbons (ie trichlorethane or brake cleaner).
MMO and a few high rpm blasts down the freeway are part of my 88's regular diet.
Here is the update............
I changed the Oil to "Rotella" 15-40 and used some MMO. Then I put a can of Sea FOam in the Intake and I have done the "Blasts". All I have noticed is that the noise seems to have gotten louder. It was cold yesterday, 30 degrees outside, so I started the xj and the "Clanking" I got was loud! It lasted jsut a few seconds, maybe 2-3, but it was loud. I talked to someone that said it sounds like the lifters.
I am planning on flushing the motor with some MMO or ATF and seeing if that will help out, but right now I am almost ready to just run it till it breaks, or just put some very heavy oil in it an see what happens. I am out of patience and frustrated by having to get under that thing over and over again for the same issue.
I dont have the time to yank the motor right now and need some advise!
The 15w-40 is going to make your problem worse as the weather cools-it'll take longer for the oil to reach your top end and cause lifter noise.

MMO can be useful, but I'll bet you get better results out switching to a Wix (or Napa Gold) oil filter and using 10w-30 or 10w-40 for the winter months. The Wix filter will help prevent oil drain down and the light weight oil will get oil to your top end quicker.
MMO is basically mineral spirits (paint thinner), a little naptha, and some chlorinated hydrocarbons (ie trichlorethane or brake cleaner).

MMO has no chlorinated solvents in it that I know of. I seriously doubt they would use it in any MMO like formulas due to the formation phosgene and HCL during combustion.

I suspect it is a high boiling aliphatic and napthenic solvent / oil mix with about a 10 Wt.

Mine was shaking the hell out of the valve cover a few days ago after a cold start. I could literally feel the valve cover knock from the sticking lifter.Took 1 quart of MMO, and 10 minutes of warm up, no more problem.
I wouldn't go more than 10-30w
Why not go with the 5-40w?

Better for coming colder winter months.
Thinner to help break up gunk.
Gunk could be so thick there isn't any flow to clear things out.