How noisy is your rebuilt 4liter?

I've noticed that my lifters seem noisy during cold operation(25deg f outside)
and when the motor gets up to op. temp. the sound kind of goes away.The best way I can describe the sound is the sound of a jack hammer..almost deisel sounding?I'm running castrol 5w30 w/lucas added.

Do these renix motors always sound like a threshing machine or what?Am I just being a paranoid new dad or will this cam wear in and quiet down?

Another thing I have noticed is a noise that had me thinking exhaust leak at first...but could'nt locate one(new header),then while installing my dynomax muffler I noticed that the noise is kind of resonating through the entire exhaust pipe all the way back to the muffler..... tick tick tick metal raspy sound?Wtf?

Are rebuilt motors noisy untill parts seat in?

I've generally found that hydraulic lifters will be a little noisy when an engine is rebuilt - but I've never kept track of how long it takes to go away. In cold weather, this can be a huge issue.

Your next oil change, put in five quarts of your favourite 5W-30, and one quart of Marvel Mystery Oil. That stuff WORKS - I've been using it for years. At the first sign of lifter noise, I'll dump it in to clean everything, and go just fine for another year or so. In cold weather (like back home,) it's a common wintertime additive (it REALLY helped my Bug warm up!)

Did you "prelube" the lifters before you dropped them in the holes - immerse them in oil, and use an old pushrod to pump the plunger? They'll take longer to wear in and pump up if you don't.

Anyhow, I'm fairly sure the noise you're hearing isn't the lifter heels wearing against the cam lobes - your engine would have stopped running, or gotten REALLY noisy, by now if that was it. Camshafts are under a LOT of stress...

5-90

Use the Marvel. It should do the job.

sorry to hijack..
I've got the occasional tick when it's really cold, adding MMO should fix that even in a well used motor? I've used it for years with model airplane motors, but never thought about putting it in the crankcase.

5-90 said:

I've generally found that hydraulic lifters will be a little noisy when an engine is rebuilt - but I've never kept track of how long it takes to go away. In cold weather, this can be a huge issue.

Your next oil change, put in five quarts of your favourite 5W-30, and one quart of Marvel Mystery Oil. That stuff WORKS - I've been using it for years. At the first sign of lifter noise, I'll dump it in to clean everything, and go just fine for another year or so. In cold weather (like back home,) it's a common wintertime additive (it REALLY helped my Bug warm up!)

Did you "prelube" the lifters before you dropped them in the holes - immerse them in oil, and use an old pushrod to pump the plunger? They'll take longer to wear in and pump up if you don't.

Anyhow, I'm fairly sure the noise you're hearing isn't the lifter heels wearing against the cam lobes - your engine would have stopped running, or gotten REALLY noisy, by now if that was it. Camshafts are under a LOT of stress...

5-90

Click to expand...

This was a remanned mail order motor that came assembled....I wondered how to prime the lifters because there was no way I was going to take the head off to get the lifters out to prime them,so I figured the rebuilder had primed them when they built it.....they would have to be primed because they run tested the motor before shipping it.......

Theoretically, then, the lifters should have been primed. Me being me, I'd still run a priming rod down the distributor hole and put a drill to it to check oil pressure - but that's just me.

It is worth noting that "run testing" a motor usually consists of putting it on a "spin rig" - a drive plate is connected to the crankshaft flange and the engine is powered externally. This still achieves the stated purpose - checking for leaks and making sure that the reciprocating assembly is not binding - but it's not "running" the motor by any stretch of the imagination. It would be more properly called "spin test" or "powered test," but that's the liars in marketing for you (this had to start somewhere...)

Still, I'd change the oil, put in a quart of MMO, and see if that does the job. If everything else is up to scratch, the MMO should work - if it doesn't, I'd be digging to find out why...

5-90

jeepdeepfreak said:

I've noticed that my lifters seem noisy during cold operation(25deg f outside) and when the motor gets up to op. temp. the sound kind of goes away. The best way I can describe the sound is the sound of a jack hammer..almost deisel sounding?

Click to expand...

Sounds like the classic cold start piston slap for which the 4.0 is well reknown. The pistons shrink in the bores when the engine's cold and once it warms up, the pistons have expanded enough to reduce the piston-to-bore clearance and the ticking noise goes away. It's not a reliability issue and there's no increase in oil consumption due to this phenomenon.
My 22k-mile-old stroker also has mild piston slap on cold mornings but after a few minutes warming up it's purring like a kitten. I run Mobil 1 0W-40 synthetic.

Dr. Dyno said:

Sounds like the classic cold start piston slap for which the 4.0 is well reknown. The pistons shrink in the bores when the engine's cold and once it warms up, the pistons have expanded enough to reduce the piston-to-bore clearance and the ticking noise goes away. It's not a reliability issue and there's no increase in oil consumption due to this phenomenon.
My 22k-mile-old stroker also has mild piston slap on cold mornings but after a few minutes warming up it's purring like a kitten. I run Mobil 1 0W-40 synthetic.

Click to expand...

dr.dyno:I remember thinking "it sure sounds like piston slap" but figured it was more likely lifter noise.....being that this is a rebuilt motor and all.The sound reminds me of a diesel motor,clack clack clack...you know?I had a lifter on an old 86 xj w/2.5 not fully primed when I installed the motor and the only sound it made upon start up and untill the motor got up to op.temp. was a real light tick...this noise here is deeper and louder than that.

I don't know about everone else,but I'm thinking piston slap is not normal on a new engine.....

5-90:When I was trying to index my dist,I saw a little carbon on top of the pistons so I think they did a "live" run test....Unless this is just a used motor they ripped me off on...

My next question is if I wanted to make sure the lifters are fully primed,how would I do that?I'm thinking take the valve cover off and remove the rockers,then pour oil down in the lifters and use a push rod to pump them?

Will they eventually prime themselves without damage to the cam or themselves?

Dr. Dyno said:

Sounds like the classic cold start piston slap for which the 4.0 is well reknown. The pistons shrink in the bores when the engine's cold and once it warms up, the pistons have expanded enough to reduce the piston-to-bore clearance and the ticking noise goes away. It's not a reliability issue and there's no increase in oil consumption due to this phenomenon.
My 22k-mile-old stroker also has mild piston slap on cold mornings but after a few minutes warming up it's purring like a kitten. I run Mobil 1 0W-40 synthetic.

Click to expand...

not to hijack buy why do you run such wierd oil. seems to me they are dumping a lot of polimers in that oil to make it span that 0-40. i always thought that multiviscosity oils wanted to be closer together lik 10-30 and 15-40 and 20-50

“My next question is if I wanted to make sure the lifters are fully primed,how would I do that?I'm thinking take the valve cover off and remove the rockers,then pour oil down in the lifters and use a push rod to pump them?”

If your engine is a rebuild and they used all new components and machined all necessary engine surfaces ect you should not have "any" noise under any normal circumstances
If your engine is that loud you have a defective engine, to say you have a unacceptable engine. And you need to return it.
I have rebuilt several engines over the years and if correctly done you will have no noise from anything inside the engine. It sounds to me that the engine you have is simply “bad”
If the valve train is making noise that could indicate loose, bad or broken,used components "Or just poorly assembled take your pick"
Or something worse like bad oil flow/pressure that could be from bad oil pump to bad engine bearing clearance or some other obstruction in the oil galleys.
If it is “piston slap” then you still have a bad rebuild job ,take it back

On another note if this was a back yard overhaul that included just installing some new rings and bearings with no machine work then that will all but guarantee a loud sloppy engine.

Just my 2cent

Dr. Dyno said:

Sounds like the classic cold start piston slap for which the 4.0 is well reknown. The pistons shrink in the bores when the engine's cold and once it warms up, the pistons have expanded enough to reduce the piston-to-bore clearance and the ticking noise goes away. It's not a reliability issue and there's no increase in oil consumption due to this phenomenon.
My 22k-mile-old stroker also has mild piston slap on cold mornings but after a few minutes warming up it's purring like a kitten. I run Mobil 1 0W-40 synthetic.

Click to expand...

wow piston slap on a low mile reman?....hmmmm how long will this low mile reman last?

bj-666 said:

not to hijack buy why do you run such wierd oil. seems to me they are dumping a lot of polymers in that oil to make it span that 0-40.

Click to expand...

That's exactly right and that's why it performs so well over a very wide temperature range. I've been using it for the last 19k miles without any problem (I used 20W-50 dino oil for the first 3k mile break-in). Mobil 1 0W-40 is the recommended oil for year round use in many high performance engines, and it performs very well in extreme conditions without losing viscosity.
My stroker runs cool even in a 120* mid-summer so I don't have any problem using it.

majic_tech said:

wow piston slap on a low mile reman?....hmmmm how long will this low mile reman last?

Click to expand...

A very long time I hope. I only hear a mild ticking noise at idle on a cold morning and it soon disappears on warm-up. It's not even close to the diesel sound that some Jeepers report from their 4.0's. The oil level on the dipstick hardly moves between 6k mile oil changes.

jeepdeepfreak said:

I don't know about everone else,but I'm thinking piston slap is not normal on a new engine.....

Click to expand...

It IS normal on most 4.0's even with very low mileages. The '96+ versions were better but DC never totally eliminated the piston slap on this engine. Just live with it.

I wonder ....seems I remember something about a car I worked on years ago with this noise in the exhaust like you described ...turned out to be a tight valve guide and the exhaust valve would slam shut making this wierd noise ....maybe maybe not dunno but it dont sound right to me for a reman I assumed it was low milage because you commented on the lifters wearing in ....where did you aquire this reman? if I may ask

It's a 0 mile motor from http://www.rebuiltautoengines.com/jeep-L6_4_242-engines.html...since you mention it,it does sound like the valves resonating through the exhaust,hope that clears up as soon as it gets broke in.Anyone else notice what I'm talking about?I know that sound was not present before I changed motors......

Dr.dyno:I have heard that these 4liters are "a loose tolerance motor"and it seems that every one I've heard has had a fair amount of valvetrain noise.With the newer 4liters not sounding so bad(maybe for the obvious reason)......what did they do to quiet the newer 4.0's down?

jeepdeepfreak said:

Dr.dyno:I have heard that these 4liters are "a loose tolerance motor"and it seems that every one I've heard has had a fair amount of valvetrain noise.With the newer 4liters not sounding so bad(maybe for the obvious reason)......what did they do to quiet the newer 4.0's down?

Click to expand...

A few things:

Lighter weight pistons
Stiffened block main webs
Main bearing cap girdle
Steel valve cover
Better valve cover gasket

The '96+ 4.0 IS quieter and more refined than the earlier models but it's still not exactly a paragon of smoothness or refinement.
My stroker is smoother and sweeter than the original 4.0 in my '92 XJ and this may be partly due to me using a '00 block with a main cap girdle, weight-matched pistons and rods, ARP rod bolts, and a 12CW crank. That said, there's still a small amount of valvetrain ticking at hot idle and I'm told it's due to the stiffer valve springs (Mopar performance) and higher lift cam (Crane 753905). I thought about swapping in a set of roller rockers but according to Bennie at Hesco, these don't help. The noise seems to be normal and I'd say that's probably true. After I switched from 20W-50 dino oil to a lighter weight 0W-40 Mobil 1 at the 3k mile mark, the valvetrain noise did increase slightly but it hasn't got worse since then (if anything it seems to have either diminished or my ears have got used to it).