Topic: 2.5 tap

[87comanche]

Well, I figured out where my vacuum leak was and it was the pinch nuts holding down the TB.  They FELT tight, but I got them to go down another 1/4" each!  Thanks to all who helped me with their suggestions and thoughts.

I drove it, open header, to the local shop, and the guy hooked up my pipes.  Not much difference, but hey my 2.5 is pretty beat, so I'm waiting for the rebuild to draw any conclusions.  

Sadly, the ticking was actually motor and not exhaust.  It's fairly new.  Exhaust guy thought "valves need adjusted."  I don't know if it's lifters, valves, or rockers, but it's a ticking that is loud and increases with engine speed.  Would taking off the valve cover and torquing the rocker bolts down to 19ft/lbs be worth a shot?  Like I said, the engine is pretty tired, but I could do without all this noise, especially pulling up to work!
 :oops:

Thanks
Tom

[Jeffy]

If its the valves then you'll have to adjust them and not just tighten them.

[Guardian7]

Great to here you found the leak though not what I expected I can relate having an 89 with those same style lock nuts. Recently installing a TB spacer I just did away with them which you can do if you remove the studs, clean the holes with a tap and change to bolts. The studs get replaced with (4) 5/16-18X1"

[87comanche]

If its the valves then you'll have to adjust them and not just tighten them.

Is there a write-up for that?  Nothing in the FSM, and I searched here with no luck.  I'm no engine internals expert, but I'm certainly willing to give it a go.

Tom

[Jeffy]

Ok, now that I think aobut it the valves might be non-adjustable which means if they tap their either loose or, more likely, the clearances are too big.

[Guardian7]

The Valves actually dont tap loose, what happens is the clearance between the rocker and the top of the valve stem becomes to great and you get valve train noise. The hydraulic lifters are designed to take up the slack as cam lobes, rockers, & push rods wear but they get old and dont perform this function well because the lifter valving becomes clogged or they get a ridge from varnish buildup which keeps them from expanding there full travel. Basically on a Chrysler engine design all the adjustment is done by the lifter and when they get replaced the cam also needs to be replaced as the lobes get worn down. The best prevention is simply frequent oil & filter changes to keep them clean and use a good quality oil to prevent varnish and sludge buildup. This is one point about Dodge/Chrysler which has always erked me after working on Chevy engines which have an additional adjustment on the rocker tower mount which can help when dealing with wornout lifter situations. If you shave the head, grind the valves & seats you also take up  some slack but this would be an un-orthodox proceedure. Additionally, if the noise gets louder with engine speed you may also need to check for a broken valve spring which is fairly common with older engines. I hope this sheds some light on the whole valve noise issue, valves themselves are made from highly hardened materials and dont usually wear, but they do crack, break, burn or pit, from other problems.

[Guardian7]

20-50 weight oil is great for old tired motors which have more slop in them because it will help fill those worn clearances, boost oil pressure throughout the engine, and even quite some valve train noises. (basically It wont sqweeze out from between moving parts as fast).

[87comanche]

thanks.  I'm going to pop the valve cover off tomorrow.

 :shock:

[87comanche]

Ok, so I did that, and the 3rd (#5 and #6 counting from the front) set of rocker arms, particularly #6, is loose.  I can move the rod around, in and out of the head, with my hand.  All of the rocker arms are tightened adequately.  How do I get the self adjusting valves to take up the slack?  I know that's a question that opens a whole other can of worms, but I'm not tearing this engine down just yet.

Tom  :x

thanks.  I'm going to pop the valve cover off tomorrow.

 :shock:

[Jeffy]

Ok, so I did that, and the 3rd (#5 and #6 counting from the front) set of rocker arms, particularly #6, is loose.  I can move the rod around, in and out of the head, with my hand.  All of the rocker arms are tightened adequately.  How do I get the self adjusting valves to take up the slack?  I know that's a question that opens a whole other can of worms, but I'm not tearing this engine down just yet.

Tom  :x

The slack should be taken up by the hydraulic lifters if it's not too much.

[87comanche]

It's probably 1/2"  Seafoam treatment worth a try??

[Jeffy]

It's probably 1/2"  Seafoam treatment worth a try??

I'd go ahead and try it.  If you're lucky it might be a partially collapsed lifter.

[Guardian7]

My question is, how is the oil flow through the lifter? Does it appear the lifter is not pumping up but is it passing oil through the push rod to the rocker?. I'm thinking an oil passage may be clogged for this lifter or it has just collapsed. Be sure that your pushrods are in the correct position and the rocker arms should be torqued to spec. A valve lifter uses simple valving and the engine's oil pressure to adjust its length slightly, thereby maintaining zero clearance in the valve train. As the engine expands and contracts, the oil in the reservoir of the lifter fills and bleeds off, providing the correct amount of valve clearance. I would also check the valve-installed stem height with the other cylinders at TDC on the compression stroke. Spin your pushrods by hand to make sure they are not bent, a bent rod will be shorter. If the valve face and/or seat were ground excessively during head reconditioning, the lifter piston would not have enough travel to reduce the clearance. This also will affect valve spring tension unless shims are installed. Inadequate oil pressure will affect lifter operation too, however, this will also affect the other cylinders.
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