Speed 20 SA. problem with replacing the sump.

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paulgarratt
Posts: 4
Joined: Fri Jun 22, 2012 1:59 pm
Name: Paul Garratt

Speed 20 SA. problem with replacing the sump.

Postby paulgarratt » Mon Jul 02, 2012 12:21 pm

When tightening the myriad nuts on the sump, I found that two of the long studs had stripped the threads in the block casting.
So the sump is not tight against the block at this point with consequent permanent ooze of oil, leading to unkind comments from owners of pristine driveways about incontinence pads.
I imagine this is not a unique problem; but is there a reasonably straightforward solution that doesn't involve massive disassembly?

In connection with the same area, should there be a paper gasket between the sump and the block? Specialists and other owners seem to be divided on this point.

Paul Garratt, 8278N

Silver Eagle
Posts: 10
Joined: Thu Aug 16, 2012 5:18 pm
Name: Philip N W Robertson

Re: Speed 20 SA. problem with replacing the sump.

Postby Silver Eagle » Fri Aug 17, 2012 9:20 pm

As far as I know in all Alvis cars of this period (Silver Eagle, Firebird, Speed models, etc.)the sump is fitted using only CLEAN joint faces and a thin coating of Hylomar or the like. If you really have a problem I think you can get away with a paper gasket no more than 0.005" thick. A 0.010" paper gasket can be used under the sump strainer.

I have found the best method is to identify all the stripped studs - by trying to tighten them, strip the threads of any suspect ones if you will, mark the dodgy ones and remove all the studs. With a fine file carefully clean off any burrs where the studs fit in the crankcase to get a true surface. Remove all gasket and jointing material with a gasket scraper from both crankcase and sump faces. Identify all suspect studs and install Heli-coils. Check that the studs screw back in easily and straight. I just "nip" the studs up, that way they will not be inclined to jam in the threads.

Be aware that there may already be Heli-coils in the crankcase!

5/16" B.S.F. heli-coils should be obtainable as a kit with the correct taps and insertion tools via an industrial fastener supplier at about £40.for a set with 10 coils.

Do not go mad with the Hylomar, apply it to one surface and smooth it down with your finger. Just so long as you can just see the colour. When the sump is refitted only a very small amount should squeeze out of the joint as it is tightened. The sump is best tightened a little at a time like a head gasket. Remember anything that squeezes to the outside will also squeeze to the inside with the potential to break off and block oilways. I do not recommend the use of silicon jointing - nasty modern stuff!

If this does not work carry a large drip tray, talk about character, and sweep up any dropped studs before driving away!

Phil Robertson 3861 Wa

paulgarratt
Posts: 4
Joined: Fri Jun 22, 2012 1:59 pm
Name: Paul Garratt

Re: Speed 20 SA. problem with replacing the sump.

Postby paulgarratt » Thu Aug 23, 2012 9:30 am

Thanks, Phil,that's good information.

Paul.


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