Engine noise, knocking

[dkmcgowan]

I have an 89 Comanche, about 120k miles on it.  It runs and drives pretty good, done a decent amount of work on it.  I use to drive it daily, but recently got another Cherokee I've been driving some.

 

So the first occurrence was when it was really cold, I had not driven the vehicle in maybe 2 weeks, cranked it up, and there was a very loud engine knock.  It got louder as I accelerated.  I moved the vehicle in the driveway, and hit accelerator a couple times, noise accelerated and got faster, really loud knock, maybe 2 minutes later or so, it stopped completely.

 

It was really cold, had been below freezing a few days, figure thick oil was maybe causing some really bad lifter noise, ignored it and moved on.

 

It never did again, but also started driving it daily again.

 

Today, I cranked it up, it's like 60 degrees here, not cold.  I haven't driven in maybe 1.5 weeks give or take, I got the super loud engine knock again.  It also still got faster and louder as I accelerated.  This time I popped the hood, couldn't tell if it was coming from the head or deeper in the engine, but a loud knock for sure.

 

It sounded louder and more of a knock than lifter noise, but it's hard to tell.

 

I also never remember, doesn't one of the types of engine noise NOT get louder or faster as you accelerator?  piston slap or lifter tick?

 

I went in and hit the accelerator a few times, it would get faster and louder.  Then I hit the accelerator really hard one time and it stopped instantly and I drove it all day, no issues again.

 

I know sometimes noises from engine can end up being exhaust, but those usually get softer and softer over time.  This got a little softer for a few seconds and then just stopped.

 

I had the head rebuilt maybe 6 months ago when I had it over doing some other work.

 

I checked and had good oil pressure, at the gauge, for whatever that is worth.  It was a good 50 psi.

 

Any ideas?

 

If it does it again I will get a video.

[ComancheKid45]

Sounds like a sticking lifter.

[gogmorgo]

I've had a dying flex plate make an intermittent knock, if it's an automatic, that sometimes went away under throttle and sometimes got louder. You might be able to see a crack if you pull off the inspection cover, shine a light in there and look for shiny hairlines.

Make sure your exhaust isn't banging against anything too.

[Incommando]

I've had a dying flex plate make an intermittent knock, if it's an automatic, that sometimes went away under throttle and sometimes got louder. You might be able to see a crack if you pull off the inspection cover, shine a light in there and look for shiny hairlines.

Make sure your exhaust isn't banging against anything too.

I have seen this, too

[cruiser54]

Sounds like a sticking lifter.

Yup. Shut it off ASAP. Wait ten seconds and re-start. Probably will be gone.

 

What oil filter are you using? 

[Fernando87mj]

Doesn't ATF act as a good cleaner when you use it in engine oil ? Help free a stuck lifter ?

[cruiser54]

Doesn't ATF act as a good cleaner when you use it in engine oil ? Help free a stuck lifter ?

Not always. 

 

Let's verify it first and we can go from there. 

1 quart of Marvel Mystery Oil in place of a quart of motor oil for 1,000 miles or more helps.