Rocker Arm Slop - Melling

[Mickey85]

Hey all,

I'm sure this has been covered but I can't find it. My 88 Renix 4.0 has 230k on it and I've been slowly restoring/upgrading it.

I went to do the Valve cover modification and noticed a ton of gunked up oil on the rocker arms, valves, and pushrods. After removing and trying to clean the rocker arms and pushrods I resigned myself to buying new ones.

The new arms and pushrods (both Melling) seem to seat properly and torque down to the correct ft-lbs but when they're NOT under tension there is a lot of play. This play is mostly left to right rather than up and down.

I've double-checked the rod lengths and they seem the same as the originals.

Is this common on the 4.0 or is there maybe a lifter or valve issue?

Many Thanks,
Mickey85

[RCP Phx]

Did you replace the rocker arm pivots? Have you tried a feeler gauge to check for any clearance? Did you check for the proper lifter pre-load?

[Mickey85]

I have replaced the pivots with new ones. I've not used a feeler gauge to check clearances and I haven't checked the lifter preload. I've just torqued down the arms to 19ft-lbs.

I guess I should start with the clearances and preload and see if that solves it!

[Mickey85]

So having spent many hours double-checking I was doing it correctly. I installed new rocker arms and rods assembly on #1&2.

I put the engine to TDC for each cylinder on the compression stroke and preloaded the lifters, then torqued to 21ft-lbs. As I rotate the engine I noticed the rocker arms are still slopy (loose left to right) although having gone through the preload with more care it seems a lot better. #2 preloaded and torqued down nicer than #1.

As I rotate the engine and check the older (ones I have not removed: #3-6) also have similar slop issues.

The pushrods SEEM to lift correctly as the engine rotates! The engine is really gunked up inside to the point where I mistook old oil for sealant! I'm wondering if the lifters are also gunked up and not operating properly and allowing the pushrods to seat correctly or I have a valve issue.

I'm thinking of buttoning her back up adding some MMO to an oil change and running her for a few hundred miles to see if that helps. Any extra advice would be great. Cheers

[1990JEEPXJ]

When at TDC my rockers would have a little side to side motion as well. Never was an issue. It didn’t seem exceeding and if there was a little motion it told me the valves weren’t hanging open at all

[Mickey85]

Ah thanks 1990JEEPXJ, that's good to hear. Unfortunately, I got the engine put back together, added coolant, and fired her up and when I went to top up the reservoir I noticed frothy brown sludge pumping in. Guess I need to do the head gasket now!

I knew the top end was going to need a rebuild soon but was hoping to hold off
for a while.

Question is, is it worth rebuilding the bottom end while I've got the engine stripped? I'm guessing at 230k miles the piston rings are fried!

Thoughts?
Cheers