Blew the rad,and the headgasket!!

Hi Ron.

I havent decided which approach I will use yet,but if there is any slight hint of pitting on the head surface,that doesnt warrant a skim,I will probably use a sealant as well!
Fortunately I do have a pair of spare heads,and a complete good engine.
Will look at headsets at a show I am going to next weekend,although I do have a couple in stock,,I think?

Hi Scott.

There has been an ongoing problem with a minor build up of pressure for a while,and ive not been able to pinpoint which of the 8 cyls its being caused by!
Its not caused any problems till now!
I know its not the thermostat as I changed that not long ago,and was getting the same symptoms after doing so.
Water pump was also replaced earlier this year due to a leak!
I am pretty sure its either a faulty gasket or if unlucky a crack in a head!
What I should of done is looked into each plug hole when I knew there was water in there,that would tell me the offending headgasket.
Its not much more work to replace both while its stripped down anyway!!
Its a good excuse for a good clean up,decoke,repaint the heads and rocker covers, inlet manifold etc and sort out the front crankseal that I think is leaking!
Just need to make sure I can get the TR6 in and out of the garage if I need to go anywhere!
 
Hi Pilkie,

If we assume that the problem is nothing more sinister than a failed head gasket, then would that not suggest that the cylinders which have injested coolant would be either 7 or 8?

As the coolant passes from the block into each cylinder head behind each of these cylinders, then it would seem most likely that one or both are the ones effected. You'll most likely find a crack in the gasket running between the coolant passage and one or both cylinders, lets hope that is the case anyway!

Ron.
 
Hi Ron,and welcome back.

Despite my 35yrs of playing with and working on classic cars of all types,I have never had the need to strip the heads off a rover V8,so many thanks for the pointer re the waterways. :)
I will have a better look at the spare heads I have to understand how it works. :wink:
I am hopefull that it is nothing more than a faulty gasket,so when the time comes for its stripdown I will report on my findings.

Right time to go play some more with the MG!
 
SydneyRoverP6B said:
If we assume that the problem is nothing more sinister than a failed head gasket, then would that not suggest that the cylinders which have injested coolant would be either 7 or 8?
Click to expand...

What about 1 & 2?
 
harveyP6 wrote,...
What about 1 & 2?
Click to expand...

Hi Harvey,

I thought of the bleed holes in the block positioned in front of 1 & 2 after I had written the post and switched to working on something else, isn't that always the way! The heads, not being sided, have the same coolant passage at either end, whereas the block has only a small bleed hole at the front and the main coolant passage at the rear, thus the vast majority of the coolant is forced to travel through the heads prior to exiting at the front into the inlet manifold.

Pilkie wrote,...
Hi Ron,and welcome back.
Click to expand...

Thanks Pilkie, it is great to be back... :D When you start to undo the head bolts, you'll almost certainly find that they initially seem stubborn to move and then "crack", this loud what have I broken sound appears. Fortunately that appears to be normal, nothing "touch wood" has been damaged and the bolt will then undo.

Had you thought about what you might like to use on the bolts when you refit them? In the P6B workshop manual they advise to use a 3M sealant, whilst the Land Rover engine overhaul manual of 1997 advised to use nothing more than engine oil. When I did mine in 1997 I used an anti seize lubricant made by Loctite.

Look forward to hearing how it goes.
Ron.
 
I have a bottle of blue threadlock thats still ok for use,so I may give them a dab of that.
Am used to torque CRACK,,it can be frightening when first experienced,as long as that is all that goes CRACK at the time!!
 
Would consideration be given to using a stud kit rather than reuse/new head bolts? I'll will be fitting the ARP stud kit to my engine rebuilt when I get to that stage so as to ensure a well sealed head gasket and do away with bolts which have to turn and tension in the block threads thus putting these threads under risk of failing with repeated tension and pulling. I much like the idea of studs where all the tension is applied through the nut rather than the threads in the block.

I aslo just realised that I haven't asked what type of gasket you have in there at the moment, steel or composite? I'm talking to this thread thinking it is a composite gasket that is giving you trouble which if it is a steel one then it will still be infomative to hear how that has failed or as Ron is suggesting a possible breach at the water passage.

Q. are the bores on the head gaskets supposed to match the bores in the block? I ask as the composite gasket I had supplied has a just under 93mm (92.9mm) bore whereas the block is standard (with a 020" rebore), I hadn't noticed this when I last fitted composite's to my daily but am looking at all these things more carefully as I rebuild my '76 engine.

The Victor Reinz catalouge has the 3500 22D gasket bore as 92.2

The 3.9 35D has two listed, one at 91.5 (has MLS against it, multi layer steel??) and one at 95.6

I just dont like the idea of having this step difference between the enging bore and gasket bore unless there is nothing to worry about but I don't thing the steel ring would compress down to somewhere near standard bore when tensioned.

I don't know what the standard steel gasket bore is if anyone can supply this for info sake?
Scott
 
Well the k-seal lasted for about 3wks,and now I cant go more than a mile without excess pressure and it certainly has that stink of headgasket failure.
The time has come,while waiting for a few bits for the MGTF to arrive,to strip it down and see whats what.
Ive located the 2 headsets I knew were about,moved the cars about,so the TR6 can get in and out of the garage,and the rover is well under cover.
Will update as and when I find out whats what.
 
Hope it goes well! You're brave to be driving with an engine that's just waiting to pressure seize... :shock:
 
Well the heads are off,"no problems encountered",and I cannot see any obvious signs of headgasket failure.
But then it only needs to be a small failure to pressurise the system.
No signs of water in the bores.
Packed up for the night now.
Tomorrow will be the clean up and will have a real good look.



 
Its all cleaning up very well,and is in great condition considering its been in daily use for the last 12yrs! "Approx 60k miles"
Very little gunge on the heads,rockers,or build up on the valves,nothing that a simple wash with petrol hasnt cleaned off easily.
Today I will be doing the final parts clean up and preparing everything for the re-assembly tomorrow.
As I have never done a RV8 head job before,I have a couple of Q's for those that have done a head gasket replacement????
The headgaskets,rocker and valley gasket and rubber end seals are the only things I will need to replace!!
BUT?
Are there any 'O' rings associated with any of them?
Couldnt see any when I took it apart,and cant see any mentioned in the manuals,but just want to check!!
Also in your opinions,should I use the std metal gaskets or a composite?
If I use the metal ones,should I run a thin bead of sealant over both sides?

Cheers all
 
Pilkie said:
The headgaskets,rocker and valley gasket and rubber end seals are the only things I will need to replace!!
Click to expand...

That's it. You'll probably see other things along the way, but that's a minimum.

Pilkie said:
Are there any 'O' rings associated with any of them?
Click to expand...

No. Just put a smear of hylomar on both sides of the inlet gasket around the waterways.

Pilkie said:
Also in your opinions,should I use the std metal gaskets or a composite?
Click to expand...

I'd just put shim gaskets back unless you want to reduce the CR.

Pilkie said:
If I use the metal ones,should I run a thin bead of sealant over both sides?
Click to expand...

No, fit them dry.

Make sure the heads go back on the side they came off particularly if you don't clean through the oil ways in the heads.
 
Thanks for the speedy reply Harvey. :D
Better safe than sorry,and make sure! :wink:
Will also replace the small hoses,and fit new spark plugs,oil filt and oil while its apart.
At least ive found the oil leak! :D
The front/rear inlet valley rubber seals were dead!!
I have got a spare inlet manifold somewhere,so will see if the water pipe under it is in better nick on the ends than the one on there now,and swap!
I have cleaned the head oilways,and 1 was totally blocked,will clean,blow through the rocker oilways as well.
Everything is going back on the side it came off.
RIGHT!!
Time to get stuck in before the last F1 race starts.

CHEERS!!! :D
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Theres no point Dave!
They show no signs of damage by burning hot or bad seating,or receeding seats,and apart from the pressurisation of the cooling system the car runs great!
If anything ever does go wrong with a valve,I have 3 spare good complete heads,and a complete engine to choose from.
 
The heads are now on as are the rocker assemblies!!
I was missing a inlet valley rubber seal so have to wait till thurs for it to arrive.
Can get all the rest fitted up while I wait,change oil and filt,adjust the autobox,and do a few bits to the MG as well.

Chris York popped in for a looksee and a natter yesterday.
I must say lucky is looking resplendant after his wash and brush up for the NEC.

Few more pics tomorrow.
 
WELL!!
Whadya know!! :(
Its still pressurising the system?
Therefore there has to be a crack in one of the heads!
This seems to be backed up by the fact that it seems to misfire for a few seconds when started from warm,and the excess pressure while standing is probably squeezing some water into a piston chamber!
Ive got a 13lb cap on and its not blowing that at the moment,and book says it should be a 15lb cap!!
Will fit a 9lb one ive got and see if it blows that!
Now all I have to do is try and identify which of the heads and which piston is giving the problem!
In hindsight I should of done that at the beginning,just incase,but then I still would of thought its just a headgasket!
To identify the culprit,I am going to run it up so theres pressure in the system,remove the plugs from one side,and drape a layer of jumbo tissue over the holes and fired it up on 4 cyl.
That way when the water is expelled I can see which hole it comes out of! :)
Maybe I need to invest in a hand held snake camera!!
Just enough time to check out 1 side,will do the rest tomorrow.
just had a thought? :idea:
Am going to connect the compressor line to the carb tower pipe,and block the other end,top up water and pressurise,saves having to run it up all the time!
Will try it out tomorrow!
 
If it's not venting the pressure out from underneath the 13lb cap then it's not overpressurising. It's designed to run with a 15lb cap so that's what should be fitted. If compression pressure was leaking into the cooling system then the pressure would be way high, more than enough to overcome a 15lb cap. There could be coolant leaking into a cylinder when it's left under pressure, which could cause that initial misfire, but that could be getting in there from and inlet manifold gasket.
I'd say it would be very rare to get a cracked head. Once you know which cylinder it is you'll be better informed.
 
Thats what ive been thinking,but the pressure gets up before it gets to temp,thus creating an airlock and not allowing water to get to open the thermostat.
At least it did before!
Maybe its just me being paranoid,or it was being a bit tempremental on 1st start up after being messed with!
just going to the shops to buy dinner now,that will tell if its the same as before.
Now its all back together I can spend tomorrow checking it out.
 
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