sealants recommended on here

[JonE]

In putting an engine back together, I've gone across the shelf today getting down all the various bottles recommended from the forum for various things. Of course, I didn't note exactly WHAT the thing was that made me go "ooh, must get some of that"...
Will any of these be the most ideal for sticking a paper gasket between block and crankcase?
LS-X
Copper-coloured silicone (which I've used on head gasket)
Wellseal (old tube)
or is something else better?

Which of the above are best for the threads on the block with water behind?

I've also found I've got bottles of Threadlock GP Blue - AND - another of Granville Bearing Fit and Studlock. Are these essentially the same please, or is one stronger?

["Slack Alice" Simon]

As far as I know, the weakest is Threadlock, then Studlock, and then Bearing Fit. I use Threadlock as a sealant on all pipe joints involving fuel, it works well.

I use silicon gaskets on the base joint, though some do not like them. I would not use silicon products on the base joint, maybe would use Wellseal if using a paper gasket.

Threads on the bloc - I'd use the middle strength Loctite. If I knew it leaked. But if it leaked any more than a slight weep, I would probably have Helicoiled it.

[Terrytuned]

ThreeBond 1215 it's not like normal silicone use it on gaskets or face to face joints. Terry.

[Steve Jones]

This is a bit of a head above the parapet job but what works for me and, so far, has never failed be it road or competition engine is:

Block to Crankcase: Threebond 1215. No gasket.
Sump to Crankcase: Silicone Gasket. No sealant.
Head to Block: Loctite Copper Silicone 5920/5980 with Head Gasket.
Exhaust Manifold to Block: Loctite Copper Silicone 5920/5980 with Manifold Gasket.
Crankcase Nose to Crankcase, Dynamo Tower to Crankcase: Loctite Black 5990 or Threebond 1215. No gaskets.
Tappet Chest Cover: Ditch the original tin and use a cast aluminium version or make one from 1/4" aluminium plate and use a sheet of Rubberised Cork Gasket.
All Studs to Crankcase and Block: Fix in with Loctite Stud Lock

Steve (with Tin Hat on)

[Charles P]

I'm with Steve (and Terry) on this except for tappet chest.
Yes aluminium but a thick-ish silicon baking sheet from Dunlem provided ample material for multiple engines for less than a fiver

In my book Threebond 1215 is in a different league from other silicon sealants.

Charles

[JonE]

Excellent stuff thankyou all.
I think I'm going to have to get some Threebond then. I like the simplicity of replacing a layer rather than adding either side of an existing one.

[David.H]

what about fuel pump to crankcase?

[Steve Jones]

Don't have such a thing but if I did, Threebond or Black Loctite 5990.

Steve

[Chris KC]

If using sealants (silicone etc) in place of gaskets you effectively end up with a metal-to-metal joint with the leak paths filled: which is a good thing, but don't forget to make allowance for the thickness of the absent gasket. It often doesn't matter but sometimes it does.

When using Loctite locking products I suggest looking them up (by the numerical product code) and reading the technical data sheet. You might struggle to follow all the data but the important part is the direction concerning disassembly. If it says 'can be dismantled with normal tools' (or words to that effect) you should be fine. The more serious grades sometimes require heating to temperatures which could destroy bearings or cranks, for example. I keep all my Loctite bottles in a box with a quick look-up card to stop me making ghastly mistakes. They are very useful, but know what it is you are using and choose thoughtfully.

[John Cornforth]

Hi JonE

Not directly what you were asking, but i have tried various sealants in the past for the top and bottom water branches. By far the best has been Loctite Si5660 grey silicone with no paper or composition gasket. I tighten the joint only a little to begin with, then some more once the sealer is fully cured. This technique seems to result in a thicker/stronger bead within the joint.