Front Cover Sealing

[KevJ+2]

After fitting a new water pump kit (great fun ) I will soon be assembling the front cover.
I know this has been discussed before but I wondered if anyone thinks that creating a better seal is possible by letting the RTV silicone cure a bit longer before joining the covers. I would think this would give more material to seal rather than squeezing out most of it and ending up with practically no sealant.
Has anyone done this or is it a poor idea?
Kev.

[gearbox]

Hi Kev, I'm at the same point you are and was thinking the same thing. However, I'm in the middle of a full rebuild. Given the fact that these engines are notorious for leaks, I am Blue RTV'ing everything including the bolts that are through to any oil galleries. I bought the Dave Bean cartirdge water pump after looking at the three 40 year old ones I had, and everyone of them appears usable, but shows signs of age in one way or another. I have read that the timing chest halves can deflect from one thou to 10 thou and testing them on a granite block I could see that happening. The New DB chest has a cast aluminum front and a milled back. The front was pretty true, but the milled back had a slight deflection. So I plan on RTV'ing the sides of the cover and around the water pump. I also will be RTV'ing the back cover to the block around the water pump. Perhaps this is overkill, but I rather do this than have to tear the engine down again. I can't believe RTV will hurt anything and rather do the belts and suspenders routine now than doing the job again. I look forward to other opinions, so if anyone else has a better solution please let me know, Thanks Allan

[rgh0]

Blue RTV is not a good sealant for rigid metal to metal assembly. Whereever you use it the excess ends up squeezing out and clogging up small oil passages if you are not careful. I only use silicone sealant very selectively in a few crtical places such as the corner joins of the sump gaskets and fitting the half moon plugs in the head at the ends of the cams. Modern engine assembly techniques use it more but they use a much denser formulation in the grey sealant you see used and it is computer controlled robot applied to get the right coverage

You will stop the leaks if you do the following I have found - but make sure all the surfaces you are joining are flat and corrossion free. then:

1. Use Loctite anerobic gasket former on the metal to metal joins such as the front cover
2. Use all the orginal cork and paper gaskets and use Loctite Aviation gasket cement No 3 or similar on them. Let it go tacky as per the instructions before tightening to help hold the cork gaskets in place.
3. Make sure the front cover pulley seal hole is centred on the crank shaft and similar for the rear seal.
4. Seal plugs with teflon thread tape or loctite pipe thread sealant
5. Use thread locker on any bolt threads that go through into oil or water passages.

The Elan facory / Lotus marques web site had a more detailed listing which says essentially similar things

cheers
Rohan

[alan]

Brian Buckland makes and fits a gasket each side of the timing cover. Has anyone tried this method ?

[DavidLB]

Be very careful with that stuff, learnt from bitter experience that it can block oil ways, use very very sparingly.

[Galwaylotus]

If you prevent all the leaks then where is your corrosion protection?!

[69S4]

What I did with mine a couple of rebuilds ago was, firstly, to check the fit between the front cover and backing plate and try to reduce the size of the gaps any sealant had to cope with - the castings were touching at the bolt holes but had significant gaps on the bits in between. A bit of time and effort with sheets of abrasive paper and I got the gaps to close to zero.

After that I used a Dremmel and a fine cutting disc to cut a longitudinal thin slot a couple of mm deep in the middle of one of the mating faces (can't remember which one now but I don't think it seemed to matter). The idea was for the slot to act as a kind of rtv reservoir so that it wasn't squeezed out when the faces came together but acted more like an O ring. RTV usage was very sparing - just enough to fill the slot, and the rest of the mating faces were coated with some anaerobic gasket formulation (again I can't remember specifically which one).

Hand on heart I can't say I'm oil leak free from that area but it's much much less than it used to be. Next time it's apart I'll probably put more effort into chosing appropriate sealents as last time I just used whatever I had to hand.

[miked]

I have used Brian Bucklands gasket paper idea with Wellseal with sucess. I use Loctite (suitable for coolant) around the pump O rings and Loctite (suitable for oil) around all the bolt holes. I have just had the engine out to change gearboxes after 2 years and at least 7-8K miles. Only oil was a slight dribble from between the cam cover out of the gasket and a slight leak from the dip stick/tube. Water pump/timing chest tight as a drum.

In fact I am just on with making up gasket templates (ally) for the pump cover for my next job then I can just cut around them and punch out the holes. As I believe Mr Buckland said in his book.

Mike

[types26/36]

lotus-twincam-f39/timing-chain-cover-gasket-t25750.html#p168809

[BobP]

I saw a video on rebuilding piston engined aircraft engines. To form some gaskets they ran a narrow bead of sealant and then ran a fine cotton thread along the entire length of the bead. I think the idea is that the thread cannot be completely flattened and so not all the sealant will be squeezed out. I guess the thread will also stop sealant from being blown out.
Haven't tried this yet but its now in my box of tricks for my next engine repair.

Cheers

BobP

[KevJ+2]

Thanks for all your replies, I think that makes about 7 different ways of tackling this job
I suppose the the biggest divide in opinion is whether or not to use a paper gasket. I must say that I am leaning more towards this as it seems the best answer for joining and sealing metal to metal. I don't know why this was not done originally when most other parts such as sump, oil pump, rear oil seal case etc. have paper gaskets. I guess most will have their own system for success but it's also a job you want to fit and forget!
Kev.

[ernest87544]

Rohan,

Good advice as usual. However, my personal experiences with scraps of teflon tape are much worse that those from bits of silicone RTV. I wouldn't use the tape on an engine.

What sort of Loctite anerobic gasket maker do you use? There are so many.

Gerry

[Galwaylotus]

As with many things in life, when a little bit is good, too much can be detrimental. Teflon tape is fine but overuse leaves bits hanging off and these are what break loose and cause the trouble. Loctite's Thread Sealer is a good alternative if you're worried about loose pieces of teflon tape.

[rgh0]

Rohan,

Good advice as usual. However, my personal experiences with scraps of teflon tape are much worse that those from bits of silicone RTV. I wouldn't use the tape on an engine.

What sort of Loctite anerobic gasket maker do you use? There are so many.

Gerry

i use Loctite 518 and yes you need be careful with teflon tape application to ensure you dont get loose bits escaping into the eingine

cheers
Rohan

[nomad]

Rohan, I will try the Locktite 518 and I agree with the RTV warning. I bought a car once with an overheating problem. When my radiator guy took the radiator apart half the tubes were plugged with bits of RTV. The water pump and thermostat had been changed by someone who really liked the stuff!

On my engine previous work had included stippling the timing chest to head gasket area with a center punch. Lot's of small punches about 3/16 inch apart. It worked well and the cork gasket had not moved though the valve cover gasket where this had not been done had shrunk and pulled in.
Where cork gaskets are used I think that it would be a good idea.

Just to throw another wrench in I'd like to suggest something I have used for years as a gasket sealer in tricky situations. Yamaha motorcycle case bond. Its what they have used for decade's to seal cases where no gasket is used. I'm out of it and if I'm not in love with the locktite 518 I will be getting more and using it on my twin cam.

Kurt.