Hi folks.
I've done a comp. test on my overheating Pinto. This was done with the engine cold and the thottle in its normal, closed state - just as a first try to get ballpark figures.

Removed plugs and got 160 - 135 - 155 - 160.
Something not right on #2

Two squirts of oil into each cylinder, turned over to distribute the oil, then got 165 - 155 - 160 - 165.

This is more suggestive of a possible broken/stuck ring on #2, although there could be an 'issue' with the head gasket between #2 & #3 as well.

All told, these figures don't suggest failure of the head gasket sufficient to cause the engine to boil after 5 miles.

Anyone have any comments or observations?

I'm now beginning to think that there may be a load of crud in the water jacket that is restricting flow. The engine was sitting unused and dry for 5 years while I built the car.

The next stages of the investigation are
1. Engine hot, redo comp. test
2. Disconnect hoses and back-flush the block, looking out for muck being dislodged.

Thanks for any (constructive!) comments!
John.

never done one, but aren't compression tests supposed to be done with the throttle wide open? just thinking the difference in cylinder 2 "could" be because it was not able to get as much air past the butterfly on the carb/throttle body?

Possibly, but all the testing was done with the same prevailing conditions (throttle closed) so it does point to #2 having some kind of problem.
I'll do it again with the throttle open...back in a while.
John.

are you sure it really is hot and not appearing to boil due to it bubbling over, which could be due to the cylinders venting into the cooling system due to a gasket leak. What is the temperature gauge saying?

I mind blowing one of the head gaskets on the 2.8 v6 and it was steaming like and old steam train all the way home but wasn't really overheating but just building up so much pressure the radiator cap couldn't cope

As you say No. 2 looks way too low. Check first that you have the valve clearances correct. It could be due to a leaky valve seat too. You can buy flushing fluid that will help clear out the block as it dissolves lime scale and rust. I’d also check the thermostat operation if you haven’t already.



[Edited on 28/5/09 by Mr Whippy]

ah, i've just seen you have a single chock carb. i thought it might have been individual ones

i think i have an idea that might be causing the over heating,

first a question though, did you rebuild the engine before putting it in the car, or was it sat there for 5 years and then just put it in and hope for the best?

if you did the later then i have an idea,

when i stripped down the pinto im rebuilding at the moment it was left standing for a year or so, when i took the head off all the water jacket holes in the head and the block, were covered completely with rust, effectively there would be no circulation between the two compartments what so ever. now im not talking a thin layer of rust, this stuff was a good 5 mm thick! i had to piece through it with a screw driver and then wire brush on a drill it to get rid of it all, if you engine has been standing for 5 years then i would say this has definately happened to yours and maybe contribution the over heating problem?

Throttle held open: 170 - 160 - 168 - 172

The last couple of times I've taken the car 5 - 6 miles, I get back home and can hear gurgly/boily noises in the engine and water escapes from the header tank cap (Sierra tank teed into bottom hose + Polo rad vent -> header tank overflow). It really does get hot - it pinks like the clappers and the block/head get 'ouch' hot!

Thermostat appears to work OK. When I fire it up and let it idle for 10 minutes I can feel the slug of hot water going into the top hose as the stat opens; the rad gets warm as you'd expect.
I set the valve clearances a few months back, after an in-situ (head on) replacement of the stem seals.
John.

first thing i'd do is try a different radiator cap. i had terrible overheating on my old honda, the pressure cap had weakend, allowing the coolant to boil and over heat. its the easiest cheapest thing to try first

if its just water coming out the cap i'd go with that. if water's mixing with oil etc, look at head gaskets

[Edited on 28/5/09 by blakep82]

Alex,
The donor was driven to my house mid 2003. I took the engine out and it sat in a corner for a few years.
Then in 2007 I took the sump off to shorten it and rebuilt the front externals - new cam belt, checked the water pump, cleaned it up and painted the block/head. But the head stayed on and I didn't touch the crank/rods/pistons.
Valve stem seals replaced in Jan 09 just before SVA, but leaving the head on.

I think you have a very valid point there, Alex. I just took a look at a new head gasket and there are some quite small waterway holes which could very easily bung up with rust and clag.
It's looking more and more like a head-off jobbie!
If the comp test variation is just rings, I can live with that!
John.

quote:

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Originally posted by omega0684
i think i have an idea that might be causing the over heating,

first a question though, did you rebuild the engine before putting it in the car, or was it sat there for 5 years and then just put it in and hope for the best?

if you did the later then i have an idea,

when i stripped down the pinto im rebuilding at the moment it was left standing for a year or so, when i took the head off all the water jacket holes in the head and the block, were covered completely with rust, effectively there would be no circulation between the two compartments what so ever. now im not talking a thin layer of rust, this stuff was a good 5 mm thick! i had to piece through it with a screw driver and then wire brush on a drill it to get rid of it all, if you engine has been standing for 5 years then i would say this has definately happened to yours and maybe contribution the over heating problem?

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I'm running a Polo rad and a remote header tank (ex-donor Sierra). It definitely holds pressure, believe me!
John.

quote:

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Originally posted by blakep82
first thing i'd do is try a different radiator cap. i had terrible overheating on my old honda, the pressure cap had weakend, allowing the coolant to boil and over heat. its the easiest cheapest thing to try first

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quote:

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Originally posted by MautoK
I'm running a Polo rad and a remote header tank (ex-donor Sierra). It definitely holds pressure, believe me!
John.

quote:

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Originally posted by blakep82
first thing i'd do is try a different radiator cap. i had terrible overheating on my old honda, the pressure cap had weakend, allowing the coolant to boil and over heat. its the easiest cheapest thing to try first

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The hot test figures look OK to me - maybe a little low on No. 2, but nothing to warrant taking it to bits just yet.

Interesting that you mention it's pinking badly - have you checked/set the timing properly and checked/set the mixture?

Incorrect settings for both of these can make an engine run very hot

As a matter of course I would thoroughly flush out the cooling system with rad flush to try and remove as much crud as possible.

Are you sure you don't just have either a stuck stat or an airlock in the block somewhere. they are a bugger for that and the air will expand quite fast when the engine gets at all hot.

check timing and mixture.

does it loose water?

what happens when it is left idling?

it does sound like an ideal job for electrolysis.

Head's off!
I've put some pics in the archive, shoing both sides of the gasket, the head and the block.
There's no apparent damage or blowing or other witness on any of them
The water was clean when drained from the block.

The water jacket holes in the gasket are much smaller than or absent in some of the waterways, but the old gasket looks identical to the new one. There's no sign of blockage in any of the gasket holes.

The head bolts were very variable in the amount of grunt needed to undo them, but this doesn't seem to have been detrimental to the condition of the gasket.

Does anyone recommend (or otherwise) opening out the waterway holes in the gasket?
I used to do similar on 100E sidevalve gaskets, but for a different reason - the center bolt had to pull down a huge area of gasket and the aim was to increase the clamping pressure. But that is not the case here, of course.
Some holes are about 5/32 diam but could easily be taken out to 1/2 inch diam or more....

John.

I have had a sinilar problem to you.

I have a V6 with a brand new Seat ally rad in a Robin Hood. Water was passing the rad cap, filling the expansion bottle and then covering the driver.

Thermostat was removed, rad cap changed for higher pressure one and water pump checked and replaced. No Joy! A compresion test was done with similar results to yours.

As a last rsort I retorqued the head bolts - I was surprised that some on each head needed tightening. Road test today and all was dry. Seems to have cured the problem (I hope)

I would suggest you flush the block and radiator and then put the engine back together. After the first proper drive, re-torque the head bolts.

quote:

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Originally posted by robinj66
I would suggest you flush the block and radiator and then put the engine back together. After the first proper drive, re-torque the head bolts.

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if it gurgles you have a air/airlock in the water system. the compression results are ok no 2 is a little low but not terrible

is your header tank the highest point on the cooling system?

has the car allways overheated or has it just started doing it?

Valve clearances may be causing the problem on 2 worth looking at, Im going with the airlock, timing , mixture theory try the cheap options first then look at the time consuming things . You can have a test for head gasket failure done at any local garage I believe the check picks up escaping gases which leak into the cooling system.

Sounds exactly like the problem i had. It was because it was plumbed in wrong. There is thread of mine that Flakmonkey cured. Alternatively look at his pics and build diary.
Steve.

quote:

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Originally posted by robinj66
I have had a sinilar problem to you.

I have a V6 with a brand new Seat ally rad in a Robin Hood. Water was passing the rad cap, filling the expansion bottle and then covering the driver.

Thermostat was removed, rad cap changed for higher pressure one and water pump checked and replaced. No Joy! A compresion test was done with similar results to yours.

As a last rsort I retorqued the head bolts - I was surprised that some on each head needed tightening. Road test today and all was dry. Seems to have cured the problem (I hope)

I would suggest you flush the block and radiator and then put the engine back together. After the first proper drive, re-torque the head bolts.

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quote:

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Originally posted by mediabloke

Or perhaps the previous owner of John's pinto replaced the gasket but didn't change the head bolts...? As they're stretch items, any retorquing (sp?) could be an illusion. Provided they're not expensive, I'd use new bolts & gasket when putting the head back on. Wouldn't consider touching the holes in the gasket though.

Francis.

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quote:

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Originally posted by ashg
if it gurgles you have a air/airlock in the water system. the compression results are ok no 2 is a little low but not terrible

is your header tank the highest point on the cooling system?

has the car allways overheated or has it just started doing it?

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quote:

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Originally posted by austin man
Valve clearances may be causing the problem on 2 worth looking at, Im going with the airlock, timing , mixture theory try the cheap options first then look at the time consuming things . You can have a test for head gasket failure done at any local garage I believe the check picks up escaping gases which leak into the cooling system.

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quote:

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Originally posted by scoop
Sounds exactly like the problem i had. It was because it was plumbed in wrong. There is thread of mine that Flakmonkey cured. Alternatively look at his pics and build diary.
Steve.

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