locost750mc
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| posted on 12/8/10 at 10:02 PM |
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Sump Sealant or not
hi,i recently rebuilt my x-flow engine, and have since done trackdays at cadwell and anglesey, upon rebuilding there has been an oil leak towards the
rear of the engine, i used cometic alloy/foam gaskets for the sump and rear crank housing, i didnt use any gasket sealant as i had been told, any gets
into the oil, can cause blockage easily. being such and old engine, i think things are not as straight or flat / smooth as they used to be. and oil
has been seeping out from the sump. At cadwell the leak wasnt that noticable. i went to anglesey on sunday, and after the sighting laps and about 5
laps hard driving, it was Pi**ing out being a very warm day aswell oil was getting quite thin aswell so would be helping. the engine bay was
splattered with oil, and feeling into the gbox housing the flywheel was dripping with oil, but was getting no clutch slip, judder or anything, and the
car was running fantastic apart from this. oil pressure is 20-30psi at tickover and about 60 when thrashed. i now have the engine a box out on the
garage floor, gearbox front seal is fine, and on the rear of the sump/crank, you can clearly see where the oil has just been pouring out. so im
wondering, im deciding to go back to the cork gaskets as these seem to provide a better seal with the foil aswell. when i fist stripped the engine
there was a type of blue sealent arround gasket surfaces, and, i had no oil leaks, so should i stick some sealent on the surfaces to be safe, could i
use some clear silicone sealent, and run a line arround the block and sump line once its tightned up to prevent any other mishaps. anyone recoment any
sealant worth using.
Thanks
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big-vee-twin
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| posted on 12/8/10 at 10:24 PM |
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Ford make a sealer think it is about 12-15 pounds but there is stuff like
thislink
Duratec Engine is fitted, MS2 Extra V3 is assembled and tested, engine running, car now built. IVA passed 26/02/2016
http://www.triangleltd.com
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procomp
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| posted on 12/8/10 at 10:27 PM |
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Hi
where to start.The better sealant is Hylomar Blue. Possibly what was being used before. It shouldn't need load all over to seal the cork gasket
should be fine.
Where the sealant is needed is over the join between the cork and rubber seals at the ends. and in the sharp corners of the rubber seals. Other than
that really just a dab between the bolt holes between the block and gasket. But that's mainly to just hold it in place whilst fitting the
sump.
Make sure the gasket face on the sump dose not have the holes dimpled proud the need to be a flat surface.
If it is a Burton sump modded for racing they have a tendency to crack close to the flange around the starter motor area on a regular basis. Only
other areas of concern is the rear crank seal thee was a dodgy batch which had very little pressure on the crank and caused a leak in to the bell
housing.
Cheers Matt
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locost750mc
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| posted on 12/8/10 at 10:50 PM |
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when i took the flywheel off, you could see where the sump and rubber sump seal joinded on the arc, there was a clear sign of oil leaking from that
point, so i suspect it was being forced out from there. i think the sump is a home made job, just cut shorter then baffled. Also, is there any
improvement on these double lip crank seals compared to the normal ones, i think normall is usualy orange and the double lip type is black. Cheers for
the fast responses guys, got some hylomar on its way.
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procomp
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| posted on 12/8/10 at 11:01 PM |
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Hi
The crank seals either usually works OK. By far the best gasket set on the market is the Victor reinz set. Bit pricey but is really good. comes in top
end and bottom end sets separately.
Only other thing to check for causing leaks is not enough crank case breathing. But only a problem if using around 6-7 k revs regular. Ie track day or
racing so worth a check when in stalled and running.
Cheers Matt
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norfolkluego
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| posted on 13/8/10 at 12:26 AM |
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On my Zetec I don't use a gasket at all, just a thick bead of oil resistant sealant (can't remember the name) from our local motor factors
(PS it's designed for the job, it's not bathroom type stuff), sump back on and allow it 24 hours to set properly before filling with oil,
no oil leak at all.
Edit.
Our old Crossflow used to leak so much and breath so heavily it was impossible to work out what oil was coming from where.
[Edited on 13/8/10 by norfolkluego]
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locost750mc
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| posted on 13/8/10 at 08:34 AM |
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I remeber that the breathing was fairly normal with the rocker and crank vented of to a catch tank. Matt small question. What will these little engine
rev to safely. When I brought the car the rev limiter was set to 6k, and I though just leave it there, untill I found people are revvin there's
much more, I know there's probably not much gains but I remeber seeing these engines produce full power at 6 k so with a lightened balanced
bottom end with flywheel, much more free flowing exhaust, what should it rev to? Sorry small question 
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procomp
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| posted on 13/8/10 at 11:42 AM |
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Hi
Depends on what spec you have. If it's to the Locost championship regs then Max power is at around 6200-6400 depending on cam timing. However
you need to be able to rev to 7k. That then becomes more dependent on valve springs ( singles ) and the fitted length and poundage. It is really valve
bounce that controls the rev limit rather than the reliability of the crank rods etc etc. The mechanical parts ( assuming they are good ) will go as
far as 8.5k - 9k.
However there's no point trying to rev past 7k as that will drop you back down nicely in to the torque range when changing up a gear if running
to the basic GT spec. Obviously if you have a higher lift cam Etc then that's a different story.
Cheers Matt
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locost750mc
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| posted on 13/8/10 at 08:54 PM |
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yeah, its all up to the 750 locost regs, it pulled all the way to 6k and felt like it wanted to go much further, not sure what diff ive got in it at
the minute tho so need to check, but ive been to donington, anglesey and cadwell and it was getting near 6k in 4th gear.
do you thing its safe for me to try the limiter at 6500 or 7000 then. As i do feel im loosing out on something somewhere.
[Edited on 13/8/10 by locost750mc]
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