Rover V8 head gaskets

[100SRV]

I decided to end the long running question "has my V8 got a dodgy head gasket" by removing the cylinder heads and inspecting the various bits. A friend told me that I would be better off using composite head gaskets as they seal better. The engine is a 3947cc 9.35 CR block, when I rebuilt it after the head skim I used tin gaskets.

Is there any truth that "composite head gaskets seal better"?

(The cylinder heads were skimmed about 18 months ago and the car had done about 8000 miles when the coolant started to smell oily - now it is like skimmed milk)

Intrigued...
100SRV

[GreenV8S]

Dunno if they seal better, they're thicker so in theory might have a little more forgiveness. But either sort should have no trouble sealing if eberything else is right. If you fit composite gaskets you will lower the CR which is not a good move if you're already down at 9.35:1. Have you found what the problem is? Better make sure you track that down and fix it before you start bolting things back together.

[100SRV]

Hi GreenV8S,
not got the heads off yet; when I do I will give them and the cylinder block a good going over. I am reluctant to use the composite gaskets for the reason you mention - I did a rough calc and based on CR being dependant only upon head volume a change from tin to composite dropped the CR to 84% of it's tin value. Not good.

Hope it is something like a head bolt that is not as tight as it should be (will check all loosening torques) or gasket failure.

What is the best policy with respect to replacing the head bolts; check and reuse if good or renew all as a matter of course.

If I find that the camshaft is in need of replacement while the engine is in pieces, is there a good, warmer alternative to the standard 3.9 EFI unit?
Cheers
100SRV

[350matt]

If everything is nice and very flat indeed then tin gaskets work fine, however this being the real world the block has probably moved a little bit and the heads as well. I'd recommend skimming the heads to a) ensure they're flat and b) to allow the fitting of the composite gaskets which have a lot more 'give' in them and tend not to leak after time.

As for cam's then the choice is large and varied, speak to someone like V8 developments bear mind that most cams require a re-map to get the best out of them

Matt

[russell_ram]

Of course the composite gaskets seal better - wtf do you think Land Rover spent hundreds of thousands of pounds developing them for if it was not to reduce the high levels of warranty claims for leaking 'tin' head gaskets?

LR were/are so convinced of that, that in service they will replace with composite on one side of a tin equiped engine only, and without any compensation for CR loss or manifold mis-matching. Of course we wouldn't do that would we, we'd replace as a pair, skim the head faces by 0.75mm from 'std' (effectively giving you 28cc type heads) to retain the original CR and manifold alignments.

If you're taking the heads off because you think you have a sealing problem, then bite the bullet, skim the heads, fit 'stretch' bolts and use composite gaskets. You won't regret it.

Russ

[350matt]

One last point if you've got the early ( pre94) heads with 3 rows of bolts DO NOT torque the bottom row ( ones nearest exhaust side) them up just use 15ft/lb or so, on the later heads these bolt holes were delted as they actually cause the head to skew and blow the head gasket

Matt

[100srv]

Thanks for the advice 350Matt, I did the lower (outrigger) row of four cylinder head bolts up to 30lb.ft when I rebuilt it after having the heads skimmed just as you suggested. It still looks as though some of hte cylinders are leaking into the valley - there are tell-tale brown stains. I haven't DTI'd this area of the block or heads yet. I took the heads off on Tuesday night, it looks as though number 8 and possible number 7 were blowing into the water jacket, there is a brown stain between the bore and water jacket (although it doesn't run all the way into the water jacket). I ran a DTI over the heads and block where the leak appeared to be; the heads seemed to be OK, as did the block although I'll have to have another look.

What should I do if the block and heads are flat? I had wondered about using an ARP stud kit instead of replacing the bolts.

When I removed the heads the ten main bolts all seemed to snap open at the correct torque figure.

I have PM'd you the photographs I took of the engine parts, I'd be very grateful for any advice. I would like to rebuild the engine and not have to wave a torque wrench at it for a very long time!

BTW, are you supposed to re-torque cylinder heads after a certain period? I remember doing this with my 2286 diesel but we never did so on hte racing Bowler.

thanks again.

100SRV

[Boosted LS1]

Composites are just dandy for sealing against uneven surfaces so I'd recommend those in your situation. If you use a set of ARP bolts you will have much higher clamping loads due to the higher torque setting and rolled threads. They won't need retorquing.

Boosted.

[100srv]

Thanks for all the advice, have dug into the wallet and ordered a pair of replacement heads machined to take composite gaskets without losing compression ratio. Looks like the heads I removed were not machined carefully - about 0.005" deviation around the head chamber at the end where the leak was.

Cheers
100SRV