Lagondaforum

Subject: Re: Severe Oil leak

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Hi,
We have side plates in stock if you are in need!

However, water mods,
Depending on how far you are going with compression ratios and other mods etc do the following work and modifications.

1. Cylinder head and cylinder block, right front 3 cylinders, looking down from above you will see very small water transfer ports taking water from the block to the head, these are usually 1/4" in dia. Increase all of these "on this area only" to the largest size you feel comfortable to do, keeping them matched to each other. We usually do these to about 7/16" or so.
2. modify the gasket to match.
3. clean and check the water transfer tubes between right and left sides, inside the block.
4. Top pipes from rear of inlet manifold to front water outlet.
These pipes should CROSS OVER right front to left rear and vice versa! they only need to be about 1/2" dia though as too big and you get no cooling on the front right 3 again!
5. If going performance route you can also make external piping to both sides and front and rear equally, this will give you a much better and much less heat temperamental V12 if you intend to drive large hills and mountains etc.

Radiator and general cooling wise.
1. Make sure you have a NEW core! old ones will never clean well enough and an engine rebuild is far more costly than a new core!
2. Remove the heat shrouds from around your exhaust manifolds and cover the exhaust with Thermotec exhaust bandage, do this well and put it on "Very Wet" This will keep hot exhaust out of your engine bay but also allow the hot air that has gone through the radiator to escape to the outside via those lovely big louvres. If you imagine the air trying to get past the engine under the car you will see why V12s regularly over heat! Especially if you remember that ALL old cars and most moderns have a positive pressure under the car when at cruising speeds! Thus hindering the cooling further!
3. Then the final cooling "Coup de gras" is to replace your fan blades for those of a Jaguar Mk11, these are of much better design, flow more air, sap less power and look good also! Easy to fit with only some hand tools and a bit of thought!
A non overheating V12 will emerge, even with a short rad DHC up the mountains! But keep the cooling system clean!

Good luck.
Julian

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Subject: Re: Thermotec exhaust bandage

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Julian,
on other discussion boards there is criticism that using Thermotec can retain too much heat in the manifolds and cause them to overheat/crack. Have you ever had this experience?

Like most V12 owners I am looking for any way of keeping the driver and passengers cooler (ie not just the car's engine!) especially in warmer weather when the passenger compartment heats up even with the roof down

rgds

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Subject: Re: Severe Oil leak

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Hi Alistair,

No, never had any problems due to the wrapping,

I have seen many cast manifolds crack due to old age and lean mixtures and or retarded ignition though! It is easy to blame something like thermotec etc or antifreeze for causing manifold cracks or water leaks but we are talking about 70 year old parts now! that were not particularly well designed or developed when new! so it's about time that some of them show their age ;o)

But no, if the manifold is absolutely flat, fitted well and not over tightened or forced on to tight studs (the manifolds need to slide on loosely before tightening nuts) then you will not have any problems that can not be attributed to old age! If the mixture is correct then the manifolds should be very cool compared to any normal more modern type engine. We regularly check manifold temps while running on our rolling road and never see over 400 deg C even at full throttle with powerful engines on the rolling road!
Though you certainly will if the engine is not setup correctly. You can easily see the manifolds glow red hot if the timing is retarded or mixture to weak!

One of the bigger difficulties is to seal the manifold to the head "without" over tightening! We use black silicone sealer which is absolutely the best exhaust sealer you will ever find!
And on engines where we are expecting high outputs compared to std, we use no gaskets and use Only Silicone sealer! But again the importance of flat manifold flange faces can not be over stressed!

Best regards,
Julian

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