rich201283
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| posted on 12/8/10 at 06:08 PM |
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Rover v8 4.6 head gasket change??
Hi
I have a range rover p38 4.6 v8
i am doing the valley gasket, should i do the head gaskets while im at it, The car is on 135000miles and i dont believe its been done b4?
There is no over heating or water in the oil, but i did notice when i drained the expansion tank a little bit of brown sludge on the side innside of
it.
do you think i should do them?
click on the link to see the image of the expansion tank
[img] http://www.locostbuilders.co.uk/upload/2IMAG0086.jpg [/img]
[Edited on 12/8/10 by rich201283]
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craig1410
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| posted on 12/8/10 at 06:44 PM |
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Hi,
I wouldn't bother if there are no major issues. The brown deposits are 'normal' in my experience and are just mild staining due to a
small amount of rust in the water from the likes of the water pump impeller.
If you want to be thorough then get a compression tester and check cylinder pressures. If you get any major variations then further investigation
might be warranted. Also, if you feel like grinding in the valves or doing a bit of minor gas-flowing of the head or matching of combustion chambers
then fair enough, take the heads off.
If all you want to do is have a look then I suggest you buy a good book on V8 engines and look at the pictures within because you will save yourself a
lot of money and time and will see the same thing. Don't get me wrong, I know how tempting it can be to take engines apart but unless you have a
purpose (eg. repair or maintenance or tuning) in mind then it just wastes money in my humble opinion.
If you do decide to take it apart then be prepared to spend a few hundred pounds on things like a camshaft, followers, springs and maybe rocker
assembly. You might need valve seats done and new valves etc etc. If you don't have a decent chunk of cash to spend on it and nothing is
actually "wrong" then leave it alone is my advice.
I hope this helps,
Craig.
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mark chandler
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| posted on 12/8/10 at 08:14 PM |
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Mine blew a head gasket at 200k miles, the over the years the head had wriggled about and fretted the surfaces.
When off I had the heads skimmed and valves reset.
I would change the cam and followers as these will be shot, not worry about the head. you can lift the a/c rad just enough to wriggle the cam out
without discharging the system, takes 1/2 a day to do.
Regards Mark
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craig1410
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| posted on 12/8/10 at 09:16 PM |
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If you do decide to take Mark's advice and change the cam, make sure you read up on the procedure first. In particular, pay attention to lifter
preload as described in this webpage:
http://www.mez.co.uk/TuningTheRoverV8-pt8.html
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sonic
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| posted on 12/8/10 at 09:23 PM |
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I would say if the heads have never been off after 130000 miles plus it is a miricle to be honest.
I have had a few 3.5 3.9 and 4.6 v8 between my dad,mates and myself and all have done the same thing,everybody thinks its the head gaskets but in 90%
plus cases it is the liners in the block same as the petrol Freelanders.
The liners move and wear through the head gaskets,the only true cure is pinning the liners and it costs a small fortune to have it done or buy a short
motor whith it done already.
I would say it the engine doesnt over heat or get preasure in the header tank then leave it alone,but if you do take it apart spend your brass on a
pinned block and then that engine is bullet proof.
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