Cylinder Head/Valve Cover Gasket?

1990 MJ 4.0L I6

1. I had to remove my cylinder head cover today due to blow by and the front PCV hose was completely falling apart from old age. What about the precurred RTV gasket on that- the FSM says to fix small cracks with RTV

2. However, it says that if the gasket is severely damaged that the entire cover should be replaced? There is no replacement gasket? Is a new cover all that necessary?

3.
http://www.off-road.com/jeep/cherokee/98/04_apr/valvecover/cover.html

This article replaced the cylinder head gasket- but RTV'ed the snorkels. Will the replacement gasket be of a "paper-like" nature?

4. I had a lot of oil leaking from around the gasket seal- is rubbing alcohol safe in the rocker arm area?

5. What is varsol?


Thanks in advance
PRL :dunno:

prljeep said:

1990 MJ 4.0L I6

1. I had to remove my cylinder head cover today due to blow by and the front PCV hose was completely falling apart from old age. What about the precurred RTV gasket on that- the FSM says to fix small cracks with RTV

Click to expand...

I suggest using both gasket and RTV - that's not a very neatly cast surface in most cases...

prljeep said:

2. However, it says that if the gasket is severely damaged that the entire cover should be replaced? There is no replacement gasket? Is a new cover all that necessary?

Click to expand...

Nonsense. There is a replacement gasket - Felpro makes them, I've bought a few. I don't have a part #, but it shouldn't be that hard to find.

prljeep said:

3.
http://www.off-road.com/jeep/cherokee/98/04_apr/valvecover/cover.html

This article replaced the cylinder head gasket- but RTV'ed the snorkels. Will the replacement gasket be of a "paper-like" nature?

Click to expand...

All the replacement gaskets I've bought have been cork, and probably 1/8"-3/16" thick. Many here would disagree with a cork gasket, but they've long been my favourites

prljeep said:

4. I had a lot of oil leaking from around the gasket seal- is rubbing alcohol safe in the rocker arm area?

Click to expand...

Yes, but it's not very aggressive. You can spray the area down with carburettor cleaner for spot cleaning, or use LPS PrecisionClean for an overall job. I can find most of the low-end LPS stuff at my local hardware store, so it should not be too hard to find.

prljeep said:

5. What is varsol?

Click to expand...

Never heard of it - probably some really spiffy $20-per-can engine cleaner. Use LPS or CRC - both are easier to find.

prljeep said:

Thanks in advance
PRL :dunno:

Click to expand...

Glad to be of help!
5-90 :lecture:

Thanks 5-90!

So any type of engine cleaner/degreaser should be ok to clean the valve cover?

Can I safely scrap the old RTV gasket off?

Best things I've found for gasket stripping are brass wire wheels (the cheap ones with the 1/4" shank - I pay about $1 each and get them by the handful) and Scotch-Brite wheels (these cost a little more - you get a backing pad and replaceable discs) for finishing. Ideally, you want to leave the surface just a touch rough when you're done, as it helps everything seat.

In a pinch, use a putty knife (it's easy to gouge the aluminum surface with a razor blade) and a Scotch-Brite pad to finish clean.

Yes, you can use pretty mkucha ny spray cleaner that can be used to break up engine crud. Like I said, I like LPS PrecisionClean, but will use Gunk or CRC in a pinch. You can hose out the valve cover without too much trouble while you've got it off, just make sure to get all the water out of it before you reinstall...

5-90

5-90, How much effort does it take you to get that cork gasket to hold torque? I've been re-torquing 2-4 times a day for the last two days, and still get a good 1/4 to one half turn on the bolt. I did RTV both sides of the gasket, so I'm assuming its just compression that is causing the torque to loosen. And, how in the heck do you get a torque wrench on that back bolt?

Overtightening the gasket, can crush it and split the bolt holes. I typically use a small wratchet (3/8") and choke up on the wratchet, holding only the head (with one hand), tighten till it´s snug and then about an 1/8th of a turn.
I clean out the bolt holes for the cover with a squirt of brake cleaner, catching the crud that squirts out in a rag, wipe off the bolts with a rag and a little brake cleaner, a dab of mild loc tite (242) (just a drop) or even on occasion a dab of silicon gasket sealer, will help keep bolts from backing out and makes retorqueing at a latter date, possible, if the gasket shrinks or hardens (usually in years).
Theoretically with silicon on both sides of the gasket, clean surfaces, and a day or two to dry, you could run the cover with no bolts. I know from experience, that they can be pretty hard to get back off.
Fel Pro makes a gasket, that has a asphaltum coating (black), acts like glue, generally don´t need the silicon, but the silicon doesn´t really hurt anything and might help seal a hairline crack. Fel Pro also makes a blue gasket, with the silicon already applied. A silicon rubber, rubber or rubber impregnated cork gasket, is nice if you want to get back into the valve cover often, glue it to the valve cover with a gasket adhesive. Rubber gaskets have a tendancy to bulge (or squirt) out of the seem (side) of the cover when not glued down, they can migrate or move around some.

I have a very simple rule - "No bolt goes in dry." I don't care what was on it when I took it out, but it will get some LocTite or Never-Seez when it goes back in. For valve cover bolts, I use LT242.

Oh - I also place a few 1/4"-20 studs around the perimeter of the valve cover area - having the studs helps locate everything for the first few bolts and saves a lot of wrestling... Ditto the oil pan, if you ever remove it...

5-90

:cheers:

Central Germany? It's too damn bad we can't get any decent beer thru customs here in the States, I can't think of anything produced here or that meets import regs that I actually LIKE... Beer's always been better overseas...

5-90

Guess you don´t appreciate it as much, when you can get it out of a vending machine. I usually drink Phillippine San Miquel or Corona, just to aggrivate the natives.
What you said, about never installing a dry bolt, is right on.

Finished cleaning the valve cover- everything went smooth. The old gasket came right off with a putty knife.

Got a cork gasket at Murray's - $5.99 and a tube of RTV for $3.49.

My mentor suggested I use engine flush after the whole procedure just to make sure any crap from the gasket change does not seize up the old I6. Any thoughts???

Something I forgot to mention, a little late now, but maybe for next time. When your scraping, the old gasket off of the block, and things are really cruddy and stuck. I use a shop vac, in the left hand and a gasket (puddy) knife in the right. Helps keep much of the crud out of the motor.
Motor flush, I´ve used it, at the next oil change I sometimes had the last bit of oil that come out, looking like sludge. Maybe it´s better to let sleeping dogs lie. The crud might be better off where it is, than where it might end up. Good oil and frequent changes, does a pretty good job of cleaning the inside of a motor, over a period of years.