Head gasket woes

[tommy red shoes]

I'm scratching my head now with my head gasket replacement on my Vitesse Mk II. I've made a couple of wrong turns on the way but I'm struggling to see the wood from the trees and need some proper help.

I blew my head gasket at the amazing Goodwood Track Day last November after flooring the pedal when she was already pinking one too many times - it really was Glorious Goodwood and although I know I shouldn't have pushed her so hard, I couldn't resist ..

Despite the billowing steam she still ran and with copious re-fillings of water I managed to get around an hour up the road before I'd used up the battery's goodwill and she wouldn't start any more - the AA took me home on a big flatbed

Stripped the head off and wiped out the mayonnaise that passed for oil (I really am very sorry old girl). Had lots of problems with the studs as they were all coated with fine black powder that bound the studs inside the head. The other half of the studs came out with the nuts on. Stud 14 refused being severely talked to (no complaints from the neighbours - they must have been away at the time) until I bought a lovely bit of stud removal engineering - £35's worth of thing like a drill chuck which finally got it out. So: new (yucky shiny) stud and hardened nut in stud 14

With all the studs out I finally managed to get the head off. Had blown between cylinder 1 and the front water channel. Amazingly small tear but that perhaps explains why she carried on running for so long

Torqued the head down, put all the bits back on, filled her up with water and new oil and found she wouldn't turn over. Suspected the battery but it finally turned out I had been stupid: I had thought I would only adjust the tappets once it had got warm but the new gasket was different enough in thickness to the old one that the valves were barely opening. That's the trouble with trying to be clever with cars - they'll bring you back down to earth soon enough

Feeling sheepish I adjusted the tappets and she turned over fine now but wouldn't fire. Fuel on the carb needles, spark was (not fantastic but was) there. Finally decided to check compression with all the plugs out: hey presto - only had a 3:1 on two of the cylinders, and 4 or 5 on three more, just cylinder 6 had a more reasonable 8.5:1 (dry - results were so bad I didn't think to try with oil)

Checked the tappets (needed minor adjustment), checked the stud torques (all fine) but still no joy and same compression ratios. Finally decided to take the head back off and see if something was fouling the gasket or if it was the wrong one. Nope - block is smooth and clean, head is smooth and clean, no indented rings around the cylinders that might require a more fancy gasket

As an aside: when I took the head off this second time water was trapped in the block even though I'd drained it and removed the side drain tap (it was too stiff to open - nothing came out when I unscrewed it). I had to siphon out the water - a good half a litre or more came out I'd say. Assuming something's blocked, which might explain the original pinking and overheating, what do I need to poke in where to clear it out?

So my question is: which of these four scenarios is the culprit, or is the answer E: none of the above:

• A The valves are not sealing properly (which would be odd given she wouldn't turn over earlier)
• B The rings have gone (the mayonnaise was salad cream yellow, not black so I'm assuming no ring failure)
• C The nuts are binding on the studs and I'm not getting it torqued down properly (my current thinking)
• D The head is warped / bent / buggered (trying really hard not to think this might be the problem)
• E None of the above (actually I'm feeling pretty beaten so now thinking this is the most likely)

tom

[thescrapman]

Tom

do you have a straight edge to check the head with?

I can't help but think the head didn't torque down properly, either due to warped head, or getting bound on teh studs.

You can check if the valves are sealing by filling the combustion chanbers with parafin or similar.

Cheers

Colin

[Richard B]

If the compressions were that bad, back to square one. As I would say the gasket has not sealed the waterways & combustion chambers.

[tommy red shoes]

Thanks for the input

Checked the head with the side of a metre long steel rule and it's flat

If its the nuts binding (don't you just hate it when that happens) what is the best way to clean off whatever the black dust is?

[thescrapman]

I tend to clean and polish them with the wirebrush wheel on the grinder.

also get the head and block spotless.

might be worth dropping head down with no gasket on and shine a bright light behind the join.

Cheers

[Richard B]

2948 wrote:

whatever the black dust is?

Carbon, burnt engine oil.

[Nick Moore]

Here's a thought... if the new head gasket is so much thicker than the old one that the valves were hardly opening, then surely your compression will be significantly lower as well?

[tommy red shoes]

Ta guys

Carbonised engine oil sounds right to me. Can you suggest a good solvent/wetter to help wash it off as I brush them?
I don't have a grinding wheel, sadly

I think you're right about the head gap being bigger but I put that down to the new gasket not being squashed yet.
The tappets were 40-45 thou when they should be 15 I think (from memory)

It suggests the studs weren't pulling down tight enough to compress the gasket.
This fits with the dirty threads / binding nuts theory.

So: what to clean the studs with? A friend had some magic carb cleaner spray that helped get gunk out when I overhauled my CD150s . Would that do it?

[Richard B]

Do you have an angle grinder? you can get a wire wheel for that. or weaker ones that fit on an electric drill.

I use Hyper-Clean.

[ferny]

Use emery paper and some penetrating oil to lubricate to get the carbon off if you have no other choice. Polish up with some wet and dry and more penetrating oil if you need to.

Does sound like something is warped to me. Could even be the block. Take a look at the gasket, any witness marks from compressing it? Are they even?

[Richard B]

put the studs in a vise and wind the nuts up and down to clean them.

Die nuts are the best for this

http://www.ebay.co.uk/itm/42-Piece-Rethreader-Thread-File-Kit-Tap-and-Die-Set-UNF-UNC-Metric-BERGEN-/251168946874?pt=LH_DefaultDomain_3&hash=item3a7ad5faba#ht_1833wt_988

These will clean/repair threads. They are not for cutting new threads.

[tommy red shoes]

Hi guys

Tried those suggestions - they were good, but it only proved the nuts weren't the whole problem

I cleaned them up, wound nuts down them (this helped more than I'd thought) and was eventually able to do all but two down to the washers by hand (one was the new stud, and if the compression was good I intended to replace the other). Thanks for the suggestions - if this had been the problem it'd have been cured by you guys

But compression was still only 3.5 on cylinder number two .. tried it wet this time and compression stayed the same, so it aint' the rings

Going to take the head off, turn it over and fill the dips where the valve heads sit with petrol (outdoors) and see if it leaks through. Then I'm going to take the gasket off and throw it, put the head back on the block direct and shine a light through to see if there is a gap at all

I'll let you know what happens when I get a warm(ish) evening free

[Pete Lewis]

always remove the studs from the block and with some oil and wet/dry sand the face completely clean ,

use new washers and high tensile nuts, std nuts will fail and the old washers distort with the 65-70 lbs ft torque on the 7/16" unf studs.

head gaskets are a  one fit only  never re use a compressed gasket


a die nut down the studs is the best cure for clogged threads , and the slott in the one end of the stud is to allow any fluid trapped under the stud to escape or you can hydraulicly blow the block as you s=crew the stud back in.


re torque the head nuts after 500 miles (as per handbook ist service) back off each nut 11/2 turn and re torque in the  fitting sequence on nut at a time .

Pete