Good or bad idea to apply thin film of RTV to oil pan gasket?

[SyberTiger]

I'm in the middle of a timing chain replacement project that obviously requires the timing chain cover to be removed. To get it off you have to remove 16 bolts bolts from the face of the cover plus 4 bolts from the oil pan that thread through the pan and into the bottom of the cover. This exposes the front 2 inches of the oil pan and obviously the front part of the oil pan gasket is what you are looking at when the cover is removed. There's no way to replace the oil pan gasket unless the pan is removed.

I'm concerned that when I torque the front part of the oil pan back onto the bottom of the timing chain cover that it might leak because I'm reusing the 14 year old original factory gasket. I'm guessing it's a bad idea or pointless since the bottom portion that touches the pan side would not or could not receive the extra RTV so why bother with the top.

Theoretically, the gasket should be clean and dry before installation but I don't have the option of a new clean gasket. So what would you do to clean the surface of the exposed part of the oil pan gasket before mating the timing chain cover? There's got to be something I can do to minimize chances of oil seeping out.

 

[Number4]

I used throttle body cleaner on a no lint towel (what I had on hand) to clean the block, cover and gasket. Just make sure that everything is clean. Then use RTV where the cover meets the pan and the block on both sides.

 

[SyberTiger]

I used throttle body cleaner on a no lint towel (what I had on hand) to clean the block, cover and gasket. Just make sure that everything is clean. Then use RTV where the cover meets the pan and the block on both sides.

So throttle body cleaner won't hurt the gasket? Looks like it's a hard plastic type of material. No leak around yours?

 

[drdoom]

I wipe that bit of gasket off with the cleaner at the same time I am cleaning the block prior to applying the RTV. Then yes a small bead I run down there. You already have the gasket so just a little. No problem. Just let it cure good before you put any oil back in. I believe I let it cure for 24 hours IIRC.

 

[Number Twelve]

RTV can't stick to an oil film or a water film. The exposed surfaces must be degreased and dry. You can do that with throttle body cleaner, Brake-kleen, acetone, mineral spirits, ethyl ether, or a dozen other strange things, like Freon 11. Mineral spirits take a little longer to evaporate than the lighter solvents. So, there you have it. Degrease, dry, apply.

 

[imp]

@SyberTiger
Clean the gasket using something which won't "eat" at it, which we have no way of predicting not knowing the gasket composition. Your dilemma dates back many decades, to when all the guys removed the front cover to install a hot cam, then had to seal that short piece of pan protruding. I've even read, in an old Ford Shop Manual, I think it was, a recommendation that the section of gasket showing be slit at the front of the block, gasket cleaned off, and use RTV with no gasket there at all. Good with the old, thin, cork-rubber gasket material. RTV is actually quite magical stuff.

Anyone doubting the magic of rubber should try to design a mold for an oil seal.......imp

 

[SyberTiger]

Yup, I understand that the corners where the block, oil pan gasket and timing cover all meet need RTV. I shall use throttle body cleaner and brake cleaner to clean up the protruding oil pan gasket....but obviously only the top side of the gasket as the other side is resting up against the oil pan.

 

[SyberTiger]

Here's a picture for those fortunate enough not to be familiar with this repair.

 

[imp]

@SyberTiger
The metal inserts around the bolt holes prevent excessive compression of the gasket material, keeping it from extruding out and eventually cracking. Looks like an elastomeric gasket. I'd clean it off, slather on RTV about a 1/8-inch bead probably along the inner edge, close to the bolt holes as possible, plenty across the two joints where the cover meets the pan flange, snug down the pan bolts first, not real tight, then the cover bolts, if it were me. Now, is the cover positively located by pins or some such (others help here), or is a "tool" recommended to center the oil seal on the damper when it's installed? Offset of the seal due to bolt hole clearances can cause seal leakage. Forgive me, never worked on 4.6L. imp

 

[SyberTiger]

@SyberTiger
The metal inserts around the bolt holes prevent excessive compression of the gasket material, keeping it from extruding out and eventually cracking. Looks like an elastomeric gasket. I'd clean it off, slather on RTV about a 1/8-inch bead probably along the inner edge, close to the bolt holes as possible, plenty across the two joints where the cover meets the pan flange, snug down the pan bolts first, not real tight, then the cover bolts, if it were me. Now, is the cover positively located by pins or some such (others help here), or is a "tool" recommended to center the oil seal on the damper when it's installed? Offset of the seal due to bolt hole clearances can cause seal leakage. Forgive me, never worked on 4.6L. imp

The cover has locator pins on the vertical side.

RTV on the top side of the pan gasket would help on that side of the gasket but since you can't get RTV on the bottom side of the gasket I'm thinking it could all be for not.

 

[imp]

The cover has locator pins on the vertical side.

RTV on the top side of the pan gasket would help on that side of the gasket but since you can't get RTV on the bottom side of the gasket I'm thinking it could all be for not.

@SyberTiger
Thanks! Those pins are a first ever for me. Years back, no such thing. That's why I threw out the question. Now, you don't want to mess with the underside of the gasket, which is against the pan. The only possible trouble spot is this: if the composition of the gasket has compressed in service down so close to the metal insert's height that tightening the parts back together will no longer compress the underside of the gasket adequately, a leak will occur. What you have there is a series of incompressible metal slugs surrounding each bolt, which control how much the gasket can be squeezed. See what I mean? New gasket has much more thickness than used, and takes lots of load to squeeze down to metal insert thickness. Old gasket has taken a "compression set', is no longer as thick as original, metal inserts obviously unchanged. So, slug on some RTV on top of the gasket after you make sure all is ready to put that cover back on, snug pan bolts, then cover bolts, then tighten pan bolts, then cover bolts. Sleep on it, no leaks. imp

 

[Number4]

Ford considers the gasket reusable. TB cleaner is less potant than brake clean and thus safer (spray on rag, not on engine/gasket.) You can use denatured alcohol if you have it. Also, don't use razor blades or metal scrapers, they make plastic versions. Use the white roloc (07528) where you can on all aluminum.

I only used RTV in the corners as the shop manual suggests. My repair took place at 150k, no leaks yet, I'm at 185k now.

 

[Number4]

Here's a picture for those fortunate enough not to be familiar with this repair.

What's holding your passenger cam in place during this pic? Or did you remove the followers?

Also, may seem simple, but make sure the ignition pulsator ring goes back on the crank faceing the right way.

 

[SyberTiger]

What's holding your passenger cam in place during this pic? Or did you remove the followers?

Also, may seem simple, but make sure the ignition pulsator ring goes back on the crank faceing the right way.

I have a cam holding tool bolted on. The HDR wheel goes back on with the sharp teeth pointing forward.