Bad lifter how do I know?

[ADV]

Started truck Friday and had a thud thud thud sound but it went away after a few seconds. Thought it was strange but it went away so drove it to work. Its my only transportation so had to drive it. Got to work sounded like I had an exhaust leak but nothing to be found. Driving it home i noticed that when I put in the clutch to come to a stop the oil pressure would drop to nothing and then come back up.


Watched a few YouTube videos and read some sounds like a lifter problem. But how do I know what one is the problem?

I have a 1987 6.9 in my truck now with ???? Miles on it.

Truck is in thw garage now until I fix it I have found something else to drive for a bit.

 

[whitehorse]

Pull valve covers and check for play in the pushrod and rockers....the 6.9 had the bushing bearing roller lifters and the newer ones have the needle bearings. I bought mine from O'Reilly, sealed power brand. I just replaced all my lifters due to the thud sound in the intake but not the exhaust...

 

[ADV]

Can I replace the bushing bearing with the needle bearing lifters?

 

[riotwarrior]

Can I replace the bushing bearing with the needle bearing lifters?

Yes you can and it could be a bad rocker arm too.

I LIKELY HAVE full sets of used rockers pushrods and lifters in stock here if so inclined?

Whats word on return line caps?

 

[icanfixall]

Most every internal part of the idi engines will cross the displacement barrier. So the needle bearing roller lifters will work fine. They are the same lifter used in the pad and chevy diesel engines. Even the Hummer engine uses them. The later 7.3 rockers will fit and work much better than the 6.9 rockers with the aluminum bridge. When you remove the valve covers you can tell if your rockers are the early ones with the aluminum bridge. they will have a taller than the rocker bridge keeping them as a pair bolted to the head.

 

[ADV]

Thanks for the help so far on this.

But school me here a bit please.
What causes them to stick?
Is just replacing them good enough or do I need to do something to keep the new ones from sticking?
And can I just pull the lifters and rockers out of my running 7.3 with a bad block?

 

[riotwarrior]

Thanks for the help so far on this.

But school me here a bit please.
What causes them to stick?
Is just replacing them good enough or do I need to do something to keep the new ones from sticking?
And can I just pull the lifters and rockers out of my running 7.3 with a bad block?

Stuck vs collapsed

Stuck to me indicates a lifter that pumps up and will not bleed down..this can be catastrophic as it can cause piston to valve kisses

Collapsed lifter is the opposite. It will not pump up and bleed down it is therfor going to tick due to the increased clearances due to the fact the hydraulic action is at the bottom of its position vs the above lifter at top of its action.

As these are a multi piece lifter either could caused by dirty oil or normal wear over itz life span.

Yes you can replace with your own parts

 

[ADV]

So if its collapsed the value will not open? Will this cause an oil pressure drop and running low oil pressure?

 

[riotwarrior]

So if its collapsed the value will not open? Will this cause an oil pressure drop and running low oil pressure?

The valve will open but you will here it clatter do to no hydraulic action taking up slack and tolerances.

Oil pressure may be affected too however much I cant say.

 

[icanfixall]

A collapsed lifter make s clattering metallic noise. You can just remove them and replace them with you other used parts. Only one issue. MAKE SURE YOU KEEP THE PUSHRODS POINTED TOWARDS THE CORRECT ROCKER AND THE LIFTER. Our pushrods have a hard ball and a soft ball end. Most of the time the copper colored end is worn off but its supposed to point up into the rocker. Mix those up and you will ruin a good engine because they wear off or wear thru the rocker. Just drill 16 holes in a 2x4 or cut holes in a card board box. Place the pushrods in that to keep them positioned correctly.

 

[79jasper]

The 12 pack pop boxes work great.

Sent from my SAMSUNG-SM-G890A using Tapatalk

 

[whitehorse]

One thing I noticed while replacing my lifters and a couple of push rods is, if you look at the bottom of the pushrod it will have a dot about the size of a pin head. That's how I figured out top from bottom on the pushrods....

 

[ADV]

If I am into the engine this far how much more work would it be to put a cam in? Always wanted to try a torque cam.

 

[IDIoit]

you gotta yank the entire front of the engine apart, but its not rocket science.
the hardest part is getting the IP gear aligned when buttoning it all up.
sometime the harmonic ballancer's can be a pain, a good puller is a must.

 

[icanfixall]

With the front gear plate removed its simple to line up the gear timing marks. It can be impossible if the plate is on the engine. The cam gear is about half the injection pump gear below the top of the plate. Heres a good pic of the gears and timing marks.