17 replies to this topic

[designermatt]

Compression I checked with engine cold a few weeks ago was :

 

170psi  190psi 170psi 185 psi number 1 being timing chain side.

 

 

After my bypass hose leaked it overheated the engine, temp guage got to about 3/4 pretty sure I didnt let it get to max on guage.

 

Figures now are

 

170psi 160 psi 170psi 160psi

 

Cylinders number 2 and 4 have dropped significantly.

 

And also the car was running okay and would idle and drive up to 70mph okay, but now it takes a while to crank over and if it starts

it might run okay for a bit but if you try to rev or pull choke out more it will cut out, or sometimes when revving be incredibly spluttery and

banging from exhaust.

 

I cant see that my oil or water have been mixing.

 

any thoughts guys, im thinking head gasket is damaged

Edited by designermatt, 30 May 2017 - 08:00 PM.

[Homersimpson]

I remember my dad overheating his clubman estate when I was a kid due to a bypass hose failure, he had to come back on an AA trunk and when he fixed it the car wouldn't start.

 

He put a little bit of engine oil down each bore and it then started (with a lot of smoke), after it cleared the engine was fine and he ran it for several more years before someone rear ended him and wrote it off.

 

Might be worth putting some oil down it and seeing if the compression improve dramatically.

 

Personally I wouldn't be too concerned as the drop off in compression isn't massive and is fairly even across the cylinders, the figures still look ok to me for a fairly standard engine.

[Spider]

When you later topped up the coolant, how much did you find you had to put in it?

[designermatt]

When you later topped up the coolant, how much did you find you had to put in it?

  atleast 3 litres , maybe 4 approximately, im pretty sure it lost all of its water and turned it to steam

[Spider]

 

When you later topped up the coolant, how much did you find you had to put in it?

  atleast 3 litres , maybe 4 approximately, im pretty sure it lost all of its water and turned it to steam

 

 

Ah, OK.

 

Mmmm,,,,, probably not good if you were seeing 3/4 on the temp gauge after loosing this much coolant, it would have gotten very hot indeed.

 

The banging you are hearing from the exhaust could be unrelated. I would check the points (if you have them) and check that the valves are closing, though, from your later Compression Tests, I'd say so.

 

The test results don't look too bad and on these alone, I wouldn't be too concerned, though much more should be looked at.

 

Try a 'wet' compression test. This is done but putting some oil (1/2 a teaspoon is plenty) in to each cylinder before re-doing the compression test.

[tiger99]

After doing that I would suggest having the head off and look for signs of melting on the tops of the pistons, but far more likely and easier to fix, have the valves out and check them and their seats. Give them a light grind with fine paste and see if they are showing good contact, a nice grey ring all round with no pitting.
Leaky valves are quite likely in these circumstances, as their heads may have overheated and warped, or burned around the edges, especially the exhausts.

The worst outcome would be warped head and/or block and partially seized piston or rings causing cylinder wall damage, which would mean a full dropdown and rebore with new piston, but A series engines are fairly robust and I suspect that will not be the case this time and it will all be down to minor valve degradation. Check the bores carefully with 2 piston at BDC and then again with the other 2 at BDC. Look for heavy scoring.

If all that seems to be ok, try checking the block and head for flatness. If ok, reassemble as it will probably be ok for some considerable time.

[designermatt]

 

 

When you later topped up the coolant, how much did you find you had to put in it?

  atleast 3 litres , maybe 4 approximately, im pretty sure it lost all of its water and turned it to steam

 

 

Ah, OK.

 

Mmmm,,,,, probably not good if you were seeing 3/4 on the temp gauge after loosing this much coolant, it would have gotten very hot indeed.

 

The banging you are hearing from the exhaust could be unrelated. I would check the points (if you have them) and check that the valves are closing, though, from your later Compression Tests, I'd say so.

 

The test results don't look too bad and on these alone, I wouldn't be too concerned, though much more should be looked at.

 

Try a 'wet' compression test. This is done but putting some oil (1/2 a teaspoon is plenty) in to each cylinder before re-doing the compression test.

 

 

Yeah I will try a compression test with oil to see the difference

 

After doing that I would suggest having the head off and look for signs of melting on the tops of the pistons, but far more likely and easier to fix, have the valves out and check them and their seats. Give them a light grind with fine paste and see if they are showing good contact, a nice grey ring all round with no pitting.
Leaky valves are quite likely in these circumstances, as their heads may have overheated and warped, or burned around the edges, especially the exhausts.

The worst outcome would be warped head and/or block and partially seized piston or rings causing cylinder wall damage, which would mean a full dropdown and rebore with new piston, but A series engines are fairly robust and I suspect that will not be the case this time and it will all be down to minor valve degradation. Check the bores carefully with 2 piston at BDC and then again with the other 2 at BDC. Look for heavy scoring.

If all that seems to be ok, try checking the block and head for flatness. If ok, reassemble as it will probably be ok for some considerable time.

 

 

Cheers for the advice about the block and possibilities. The engine I put in was second hand and had some light corrosion in the 2 bores with the lowest compression, the bores in general had a tiny lip at the top of the bores, nothing major at all , My old engine was the same and ran great. The cylinder head that came with it I didnt strip down and clean etc so perhaps the cylinder head and valves want cleaning/lapping in etc. check for warping.

 

So the plan is ive got an old cylinder head off my old engine which was okay, and have stripped it down and very carefully put the valves in a drill and ran light sand paper on the carbon deposits and valve faces to decoke them ,  I need to just lap them in now so the valve and seat are in good condition, also im going to fit new headgasket kit as a matter of course because there so cheap.

 

Although I need to carefully inspect my bores and block face like you said and inspect for any new serious damage/wear

[dyshipfakta]

With that much water gone the temp gauge won't read well if at all. So I think I has gotten much hotter than it suggests. I think I would pull the head off regardless for the sake of afew hours and a gasket.

[ACDodd]

Overheating can cause distortion of the valve seats leading to loss if seal. In servers cases it can also lead to tempering of the piston rings, causing a loss in tension, leading to permanent loss of seal. In all cases a cylinder leakage test will tell you how bad it is and where the problem lies. Compression testing will not identify where the problem lies.

Ac

[designermatt]

ok so found out some interesting info...

 

I should first say in my earlier post where i got a lower compression reading the second time was when the engine was slightly warm. And that is the only reason the compression was lower because today I read the compression from a cold engine and it was exactly the same.

 

So before and after it overheated a few times the compression figures are the same, so that tells us something.

 

Now from cold I also put oil in cylinders and got different figures reading:

 

cylinder number 1 radiator side of engine first

 

185psi  225psi 195psi  215 psi

 

Now im not sure what the point of the oil test shows if anyone would care to elaborate that would be good?

 

Although I think its correlated to the bore wear as the more worn bores have lower results.

 

So anyway , I have whipped the cylinder head off and removed gasket etc.. and I cant see any obvious signs of damage on it.

 

Only thing I noticed was cylinders 1 and 4 were more dry and normal carbon fouled, and the inner 2 where more oily and carboned up. Very wet with oil.

 

 

And to add, I also reconditioned my other cylinder head today , by lapping all valves in and fitting new valve stem oil seals.

 

Now I will try upload some pics of the bores etc...

[designermatt]

Sorry for massive pictures

 

 

 

 

 

 

 

 

Please Note That last picture is of the other head ive reconditioned

[designermatt]

Well i slapped on the new head very carefully and torqued everything down in 3 stages making sure I was extra careful to gradually get everything evenly torqued etc...

 

However when she started up she still had the same misfire and was only running on 1 or 2 cylinders, and evidently to the back and sides of the block water was coming out and I mean a lot of water coming out between the cylinder head and block.

 

My final conclusion is that the block is warped not allowing the head to flush up and obviously water coming out inbetween the loosest spaces.

 

If anyone has any views or ideas other to this Im all ears , but I think this engines had it.

[cal844]

You can flatten the block deck but you'd need to be meticulous

[Rorf]

Honest opinion - cylinder bores look bad. I would advise a full engine rebuild and definitely skim the head and top the deck, and use a Payen head gasket.

[tiger99]

Can you take it apart again and show us some pictures of the block, head and both sides of the gasket? Not sure what we will be able to tell you, but worth a try.

If the block does need skimming by a few thou, label the piston so they go back in the same bores and take them in for skimming too. That will also give a good opportunity to check the bores fully.

I am beginning to think that you may have a cracked head or block, or porosity, so have close scrutiny. I do hope it is something else. You could ask for crack testing prior to skimming. No point paying for a skim if it is a crack.