Replacing head gaskets
Discussion
Hi Folks
I am about to take the car off the road to do some work, including changing the L/H exhaust manifold and valley gasket. I came across this article on the RPI engineering site http://www.v8engines.com/engine-4.htm basically stating that all pre 96 Rover V8 engines will have leaking head gaskets to some degree. I just wondered whether some of you more knowledgeable members are in agree with the assumption and if it would be a good idea for me to change the gaskets whilst I am carrying out work?
Cheers
Steve
I am about to take the car off the road to do some work, including changing the L/H exhaust manifold and valley gasket. I came across this article on the RPI engineering site http://www.v8engines.com/engine-4.htm basically stating that all pre 96 Rover V8 engines will have leaking head gaskets to some degree. I just wondered whether some of you more knowledgeable members are in agree with the assumption and if it would be a good idea for me to change the gaskets whilst I am carrying out work?
Cheers
Steve
Hi Steve,
Funnily enough I read the same article this weekend. Their comment is based on the fact that pre-serp engines had 14 bolt cylinder heads, and that the outer row of 4 bolts on each bank is a design flaw which causes the heads to be pulled over to one side, ultimately leading to HG failure. The later heads only had 10 bolts, although you don't need to go to the expense of replacing the cylinder heads to cure the problem. I have 14 bolt heads, and it is accepted practice to either leave out those bolts completely, or use them but at a greatly reduced torque level when tightening. My heads don't have the 4 bolts fitted at all (since about 2000), although I do have ARP studs fitted. I will actually be replacing my O/S HG shortly, as my local specialist reckons there is some leakage, which I've suspected for a while. It's not done badly to last 15 years I suppose, given the use I put it to with trackdays etc. If you need to change the valley gasket anyway, for relatively little extra expense, I guess it would make sense to do the head gaskets. Doing the valley gasket gives a good opportunity to look at the condition of the cam as well. On a standard 350 engine I wouldn't bother with ARP studs though, unless the standard head bolts are stretch types - I can't remember. If they are, rather than buying a new set, might be worth fitting studs.
Edit: would recommend using decent (Elring) composite gaskets)
Funnily enough I read the same article this weekend. Their comment is based on the fact that pre-serp engines had 14 bolt cylinder heads, and that the outer row of 4 bolts on each bank is a design flaw which causes the heads to be pulled over to one side, ultimately leading to HG failure. The later heads only had 10 bolts, although you don't need to go to the expense of replacing the cylinder heads to cure the problem. I have 14 bolt heads, and it is accepted practice to either leave out those bolts completely, or use them but at a greatly reduced torque level when tightening. My heads don't have the 4 bolts fitted at all (since about 2000), although I do have ARP studs fitted. I will actually be replacing my O/S HG shortly, as my local specialist reckons there is some leakage, which I've suspected for a while. It's not done badly to last 15 years I suppose, given the use I put it to with trackdays etc. If you need to change the valley gasket anyway, for relatively little extra expense, I guess it would make sense to do the head gaskets. Doing the valley gasket gives a good opportunity to look at the condition of the cam as well. On a standard 350 engine I wouldn't bother with ARP studs though, unless the standard head bolts are stretch types - I can't remember. If they are, rather than buying a new set, might be worth fitting studs.
Edit: would recommend using decent (Elring) composite gaskets)
Edited by Number 7 on Monday 12th October 20:27
I changed the camshaft a few months ago, shame I had't read this article at the time. There is no sign of water ingress in the oil and I can't see any bubbles in the header tank-can't smell any fumes either. The overflow does tend to spill over into the catch bottle at some time in a run, so this, combined with the fact that I keep developing an oil leak and i can't get rid of'pinking' completely suggested that the may be too much compression.
If I fit the composite gaskets, does that alter compression and would I need to make any adjustments anywhere to allow?
Thanks for the responses guys
Steve
If I fit the composite gaskets, does that alter compression and would I need to make any adjustments anywhere to allow?
Thanks for the responses guys
Steve
Idealy you should skim the heads to fit composites; however on my 3.5L engine I had slightly different compression ratios on each bank so you should proceed with caution. I skimmed mine half way so I have material left to play with.
The advice to get good quality gaskets is spot on - I fitted Grimmers composite gaskets and had to repeat the exercise about a year later. I now have Federal Mogul 'Felpro' gaskets which seem much better. I couldn't get Elring Klinger gaskets for the 3.5L bore size.
The advice to get good quality gaskets is spot on - I fitted Grimmers composite gaskets and had to repeat the exercise about a year later. I now have Federal Mogul 'Felpro' gaskets which seem much better. I couldn't get Elring Klinger gaskets for the 3.5L bore size.
A compression test can tell you a lot about the state of the engine, and also provide useful information about deterioration over time when compared to previous tests.
as for the CR, depends what is already fitted. If they're the original steel type, then yes, because the composites are thicker, you will lose compression, but the upside is that they are better at sealing the heads if not in perfect condition. In addition, if they are the originals, they will now be nearly 30 years old.
as for the CR, depends what is already fitted. If they're the original steel type, then yes, because the composites are thicker, you will lose compression, but the upside is that they are better at sealing the heads if not in perfect condition. In addition, if they are the originals, they will now be nearly 30 years old.
They have to be pretty bad for the compression to drop a lot.
I had a known blow on cylinder 8 and it was still showing good compression. Maybe slightly lower than the others but nothing you could put your finger on.
A much better check is whether there are bubbles coming out of the cooling system and what gas they are when running the engine. I bubbled mine though lime water and it showed the classic chemistry lesson signs for CO2 - a milky precipitate formed.
It's an easy check to make and if you need lime to make your lime water just drop me a PM and I'll send you an envelope full of white powder through the post ;^)
I had a known blow on cylinder 8 and it was still showing good compression. Maybe slightly lower than the others but nothing you could put your finger on.
A much better check is whether there are bubbles coming out of the cooling system and what gas they are when running the engine. I bubbled mine though lime water and it showed the classic chemistry lesson signs for CO2 - a milky precipitate formed.
It's an easy check to make and if you need lime to make your lime water just drop me a PM and I'll send you an envelope full of white powder through the post ;^)
SteveBikeandAuto said:
Thanks for all your contributions and advice, I'll investigate further and let you know what I find; taking everything into account, I will probably change the gaskets as I will have the engine stripped down to cylinder heads anyway.
Cheers
Steve
If you got the engine stripped to the heads, it's only going to take a few extra hours to swap. so its a good idea to do it now, if your planning on keeping. you can then have a good look at the pistons and bores.Cheers
Steve
Gassing Station | Wedges | Top of Page | What's New | My Stuff