Blue Hylomar

[jono]

I'm in the process of removing my engine after 13k miles due to a myriad of oil leaks.

Thinking about how to achieve a leak free engine this time (some hope!).

I've used Hylomar on other engines before and never had any leaks, and I like it - is there any place for this in a twincam?

Last time I used Wellseal and the various different grades of Loctite as per recommendations without long term success.

I recently used Wellseal on a diff housing gasket and that leaks.

Appreciate any views on this

Jon

[rgh0]

Oil leaks in a twin cam have many possible causes that fall into 5 general categories

1. Poor original design e.g. the front cover retaining bolt arrangement that was restricted by the original bolt holes available in the block.
2. Poor fitting of components - e.g. distortion and corrosion and re-machining making the component fits poor, poor machining of new parts also can add to this problem
3. Poor assembly techniques - e.g. not evenly torquing up the components to ensure the gasket is correctly and evenly compressed by the right amount.
4. Inappropriate use of sealant materials. This tends to be what people focus on looking for the magic sealant that can compensate for the first 3 problems.
5. Problems that don't relate to the static gasketing e.g. poor centering of front and real crank seals or wear on the seal contact faces.

Wellseal, Hylomar or Loctite Aviation Gasket sealant as a paper or cork gasket dressing I suspect all work equally well if used appropriately and the first three things are also correct to the degree possible. Personally I use Loctite Aviation Gasket sealant with good results ( also sold under the Permatex brand)

On non gasket joins such as the front cover to back plate I use loctite 518 anaerobic gasket former.

I only use silicone gasket former ( I use Loctite high temperature coppemax) on a couple of very small areas, such as the join between the sump side gaskets and the semicircular cork sections over the crank at each end on the bottoms of the semi-circular rubber inserts between the head and cam cover at the ends of the cams.

cheers
Rohan

[jono]

Many thanks Rohan,

As a point of interest what would you use on the cork sump gasket? (I used the black Loctite silicone)

And, are there any alternatives to the cork sump and timing chest gaskets - the timing chest gasket has extruded and seems to have separated where the layer of foil is? I understand that Burton may do some form if fibre 'competition' sump gasket.

[Lyn7]

Hi Jon. I have used the competition gaskets from Burton, on the sump and the cam cover. I am very impressed. Unlike the cork they do not compress and can be torqued down evenly. I have even re used them with success! On the subject of sealant choice and leaks I wish you good luck . Cheers, Lyn...

[Grizzly]

Permatex Ultra Grey or Aviation Gasket sealant for me......

100% agree that the key is in making sure the mating surfaces are flat (i had a nightmare trying to stop oil leaks until it was pointed out i had a warped Cam cover ) also follow the instructions on the sealer amazing how many people slap it on then wounder why it leaks?

[Davidb]

I would add one more item to Rohan's list of causes-poor or blocked engine breather.

[jono]

David,

Funny you should say that as I'm thinking that's a big part of my problem - did you experience this and if so what did you do?

I was so concerned I did a compression test which found that all cylinders were 195psi +/- 2 pist which I think seems okay?

I'm half expecting to find the rubber oil drain tube constricted or otherwise blocked as this issue did not start until around 5k miles and got progressively worse and, recently, much worse.

I have been thinking of putting a second breather on the engine perhaps using the old distributor hole (I'm on wasted spark) or else the old pump aperture. I may end up drilling the cam cover and putting one at the top of the timing chest.

Any views?

Jon

[rgh0]

I use Loctite aviation casket sealant on the sump gaskets. I cover one side and fit them to the block after allowing the coating to go tacky over about 15 minutes. I then cover the other side and again allow it to go tacky before bolting the sump down lightly. I apply a small amount of Loctite high temperature CopperMax silicone at the corner joins of the end semicircular segments with the flat side gasket elements. I also normally need to trim a couple of mm off the ends of the semicircular seals as they are typically to long which makes them hard to keep properly in place as the sump is bolted down.

I then torque the sump down evenly after an hour or more watching the gasket compression and aiming more for a 30% compression on the cork gasket rather than the specified torque number on the bolts. The bolts need re torque a couple of times after the engine heat cycles so i use socket head bolts as its easier to get at them all with an ball headed Allen hex key once the engines in the car and the gear box fitted.

Be careful what rear seal housing you use on an engine as the later Ford one was wider where the seal fitted to accommodate the rubber seal they used. Lotus always used a narrower gasket seat width that matched the front seal width on the Lotus front cover casting so a similar width cork gasket was used at each end

cheers
Rohan

[RichardHawkins]

Jon,

My engine has not run yet.

Rohans advice is good as always. I checked all joints with a feeler gauge by gently bolting together metal to metal, and seeing what the gap was at the mid point between the bolts. I aimed for a gap no more than 0.002", not always achieved.

Automotive joints are often flimsy, and it is quite easy to distort the flange by enthusiastic tightening. My sump was a good example of this, and had been distorted at every bolt hole. To exaggerate the sump flange went up and down like a switch back. One of my friends thinks that modern oil leaks through cork gaskets, not round them. I cut my own sump gasket from Klinger Sil C4106. I bought a Cometic (I think this is the American gasket you were thinking of) sump gasket, but thought it was too hard. I also bought from Burton Performance a "competition sump set" (I think that's the correct name), but was not convinced the gasket material was appropriate.

I tested the following by sticking pieces of gasket to aluminium and steel, I don't have any bits of cast iron.

Hylomar (blue)
Welseal
Loctite 518
5203
5900
5910
5922
5980

I concluded that Loctite 5910 gave the best results.

5910 only comes in a large cartridge with a big nozzle. You don't want to use too much or it will end up in the lubrication system. I bought small nozzles and adaptor for the cartridge from Adhesive Dispensing Ltd. I stuck the gasket to the block with 5910 gently bolted in place, then when the 5910 had cured removed the sump, applied 5910 to the sump and bolted together.

For the cam cover and timing case to head joint, I have used Viton, stuck to one face only with 5910.

Someone else mentioned the crankcase ventilation system. I had a vehicle with a Rover K series engine. If I removed the dip stick whilst the engine was at tickover the engine would almost stall. I think that modern crankcase ventilation keeps the engine at slight negative pressure, so that if there is a small leak it will be air in, not oil out.

Hope this helps

Richard Hawkins

[Davidb]

Jono: I did have a problem with the breather on my engine and using the fuel pump orifice as a breather turned out to be a bad idea -too much oil is being flung around in that area! I tried welding a baffle plate over the hole in the plate that covers this orifice in my engine but it made little difference. The answer was to install a breather in the timing chain cover-it is known as a "Hart breather" I believe after Brian Hart the engine builder. Mine is just a 90 degree threaded fitting but TTR sell an expensive adapter too.

[jono]

Thanks David, I had considered using an A series breather can and brazing it to an adapter plate to overcome that problem but I think i will stick to the simple route and do what you have done.

Did it fix your problem and what diameter fitting did you use?

Cheers

Jon

[Davidb]

Yes, it fixed the problem-no leaks now. I used a fitting with a 1/2 bore.

[mbell]

On the breather I've been wondering about possible improvements to the standard setup. I don't have issue as but think its weak area on most engines and wondering if there is a way to improve it with out having to drill camcovers etc..

I was wondering if re-routing the standard breather to the inlet end of the air box would be worth while. It would spread the crankcase fumes across all the cylinders instead of just number 4 which would be good. But what I am really interested in thou is creating a bigger pressure difference between the engine block and intake to increase the airflow through the breather system. I am not up on the physics here to know if if the would be a good low pressure area in the airbox/neck to route the outlet too or someway to take advantage of the Bernoulli effect.

Anyone have any thoughts?