if it starts leaking again a few options

1#lift the motor out and work with space to drill and tap properly

2#if not attached to the car -- trade it


3# if attached to the car
I would start looking for s/h short engine (just the bottom end or motor )
its a real problem

cast iron or aluminium and small threads damage like you have is never easy

very difficult to thread and tap straight unless the engine is out of the car

this will always be in your mind about the next service / a leak / another fix

 

So, what you are saying is that I should use the gasket plus the skim coat of sealant, NOT the gasket, skim coat and the 6mm bead of sealant that would have been used without the gasket?

 

Perhaps over thinking the issue.

There are several options:

1) Use the 6 mm bead of sealant only (no gasket) and follow the Toyota diagram as to how and where to apply it.

2) Use a gasket plus a bead the sealant (diameter = your estimate). Follow the Toyota diagram for sealant application on the pan. Also apply a bead of sealant to the engine.

The gasket will compensate for a less precise sealant application.

3) Do No 2 but also apply a skim coat to the gasket. This allows sealant to sealant contact when all parts are mated.

No 3 allows (in my opinion) maximum forgiveness in sealant application (bead size and location) and bolt torquing variations over No 1.

Few people actually measure the sealant bead width and will just guess. It can be very difficult to apply a precise 6 mm (or whatever) bead of sealant as a small tube of sealant is used. This is not like using a caulking gun where a uniform bead can be applied. Most people apply sealant as best as possible, adding more here and there if needed

The issue is not wanting a leak. No 3 (in my opinion) allows the best chance of not leaking.

You can eye ball the pan and block surfaces to determine how large a bead to apply. The idea is when the parts are mated and bolted up, the sealant will under pressure flow to the width of the joined surfaces and ideally slightly squeeze out of the joint. This squeeze out is proof there was enough sealant applied to span the joint width. If myself would estimate 4-6 mm on both surfaces and call it good.

Then allow the sealant to fully cure.

 

I'm not sure I'm communicating very well. Toyomoho, this is what I plan to do. Let me know if this is correct or not correct:

I'm going to skim coat the gasket on the side that contacts the oil pan. I'm going to position it and let it cure before I do anything else. Then, I'm going to skim coat the gasket on the side that contacts the engine block. Immediately after, I'm going to apply the recommended 6mm bead of sealant in the pattern that Toyota suggests. I will then install the pan and torque the bolts to 80 in-lbs as recommended by Toyota.

Correct, or not correct? Thanks again, Toyomoho!

 

I may be making this two complicated so let's start over. Note, the suggestions below may be different from previously ones to simplify things.

Toyota used sealant only (no gasket) which was applied to the pan per the Toyota diagram. To seal using only sealant requires a more precise application method and larger bead diameter. If your using a gasket you don't need to be as precise or as large of bead diameter as the gasket should seal, the sealant is just insurance.

When using sealant in an application like this (two parts mated together), for best results don't allow any sealant to cure (skim coat), then attempt to apply more sealant (the bead of sealant) that will contact the old.

You want to fully assemble and torque up the parts BEFORE the sealant cures! You want all sealant applied to cure as a unit after assembly not some before and some after.

Take note of the working time of the sealant as stated on the product label. You want the sealant applied, assembly put together and torqued up within this time period.

Skip the skim coat.

Apply sealant to the pan seal per the Toyota diagram. Meaning route the sealant around the bolt holes per the diagram. The diameter of the bead need not be as large as the gasket should do the sealing. You just want some sealant on the pan which will then contact the gasket when installed and fasteners tightened.

Position the gasket on the pan, the sealant will hold it in place.

Apply another bead of sealant the now positioned gasket. Again the diameter not be as large. You just want some sealant which will contact the engine and gasket when the pan is bolted up.

When applying the sealant note the gasket will doing the sealing, the sealant is insurance. Thus you don't need as much. A thin (not skim) coat should be enough

Install the pan and the bolts/nuts.

Start snugging up the bolts/nuts. When snugging up the bolts, alternate the fastener location around the pan to allow the pan to be uniformly pulled up to the block. Meaning don't start at one fastener and move to the one next one, then the next. Work around the pan. You want the pan (and gasket) pulled up uniformly to the block, not just the area you are started tightening the bolts at first.

As the fasteners become tight watch for the gasket compressing. If the gasket it starts to squeeze out too much (as can happen with rubber gaskets) tightening the fastener.

Tighten all fasteners to a uniform torque which may be 80 in-lbs or less depending on if the gasket starts to squeeze out to much.

Note the original Toyota designed used sealant only which a portion of filled a slight groove in the pan. When the bolt were tightened up, eventually the sealant squeezed out and the pan made hard contacted the engine. Then the fastener started to torque up. If there is a gasket in between the pan and engine, the gasket will compress. It is possible if too much torque is applied some gasket materials will just squeeze out under compression.

 

Order:

1. Pan >

2. Smaller bead of sealant in the pattern Toyota suggests >

3. Gasket (on top of #2) >

4. Smaller bead of sealant in the pattern Toyota suggests (and on top of the gasket) >

5. Engine block

No skim coat, do not wait for anything to cure.

The Haynes manual suggests that you "tighten the bolts from the center out." Does the Nissan diagram below illustrate what they mean? Start from the passenger side, then across to the driver's side? It also says to do the tightening in "three or four steps," meaning, tighten a little at a time for each bolt.



Correct?

 

You got the idea.

Apply enough sealant to spread between the gasket and mating surfaces when mating up and fastener tightening. Or you can spread it yourself before mating the part up.

Since the gasket is doing the sealing the amount of sealant need not be as great since it does not need to fill voids or gaps between parts or depressions in the pan flange. This type of filling is needed if only using sealant (no gasket).

Might think of the sealant in this case as glue. Once the fasteners are tightened you want all parts to be glued together. The gasket rather then glue (sealant) will span any gaps, etc. and too much applied glue will just squeeze out. More glue may not be better.

If the pan flange is for some reason bowed in the middle, tightening the middle first will straighten the bow as the outside of the pan is still free to move.

Center out tightening would allow any gasket movement to shift outward providing relief. As opposed to tightening from outside in where in theory the gasket being now retained at the ends on the outside could bind up. This can be a problem on long gaskets.

The bolt tightening diagram is fine. They key is the three of four steps to work up to fastener torque. This allows both sealant and gasket time to move around.

More sealant is not always good but the area of sealant application is important. Put the sealant on the side of the fastener holes as shown in the Toyota drawing. This keeps the oil in pan from reaching the fasteners and possible dripping out.

Sealant can act as a lube allowing a gasket to start to squeeze out if too much torque is applied. Watch for this and if it happens move onto the next fastener.

Everyone has their own methods of installing gaskets and torquing fasteners. Unless a critical application one can be just as good as another.