MautoK
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| posted on 28/5/09 at 01:08 PM |
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Compression test
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.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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blakep82
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| posted on 28/5/09 at 01:11 PM |
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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?
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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MautoK
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| posted on 28/5/09 at 01:15 PM |
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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.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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Mr Whippy
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| posted on 28/5/09 at 01:16 PM |
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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]
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blakep82
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| posted on 28/5/09 at 01:28 PM |
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ah, i've just seen you have a single chock carb. i thought it might have been individual ones
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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omega0684
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| posted on 28/5/09 at 01:28 PM |
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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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MautoK
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| posted on 28/5/09 at 01:35 PM |
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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.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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blakep82
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| posted on 28/5/09 at 01:44 PM |
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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]
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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MautoK
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| posted on 28/5/09 at 01:48 PM |
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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:
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?
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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MautoK
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| posted on 28/5/09 at 01:50 PM |
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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:
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
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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blakep82
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| posted on 28/5/09 at 01:55 PM |
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quote:
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:
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
i thought mine did too.
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]
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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nick205
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| posted on 28/5/09 at 03:35 PM |
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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.
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cadebytiger
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| posted on 28/5/09 at 03:40 PM |
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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.
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02GF74
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| posted on 28/5/09 at 04:13 PM |
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check timing and mixture.
does it loose water?
what happens when it is left idling?
it does sound like an ideal job for electrolysis.
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MautoK
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| posted on 28/5/09 at 04:43 PM |
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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.
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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robinj66
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| posted on 28/5/09 at 05:40 PM |
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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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mediabloke
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| posted on 28/5/09 at 06:10 PM |
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quote:
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.
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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ashg
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| posted on 28/5/09 at 07:16 PM |
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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?
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
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austin man
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| posted on 28/5/09 at 08:22 PM |
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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.
Life is like a bowl of fruit, funny how all the weird looking ones are left alone
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scoop
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| posted on 28/5/09 at 08:30 PM |
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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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MautoK
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| posted on 28/5/09 at 09:08 PM |
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quote:
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.
@robinj66: That sounds pretty much the same as I've had. There's a small amount of crud in the water jacket - feels like about 1/8 to 1/4
inch deposit of rust flakes. Maybe fully drain the water and remove whan I can with a greasy stick or try vacuum cleaner with a small nozzle to suck
it out.
I've got a new set of bolts coming - they are the stretchy Torx type - and new gasket in stock.
Tomorrow I'll scrupulously clean the head and block faces ready for re-assembly...
quote:
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.
@Francis:
That's entirely possible! I was told by the vendor of the donor car that the engine had come from another vehicle so it's history is
somewhat indeterminate! Mind you, it ran well and sounded good so I didn't disturb what didn't need disturbing - with a view to a full
rebuild later. Anyway, new gasket and bolts will go into it this time (only £10 for the bolts) and I'll carefully clean the bolt holes.
I think, on reflection, I won't alter the gasket - there are two large (17 mm square) waterway holes at the very back end of the gasket which
should give good flow. The smaller ones ( 4 @ 4mm dia on the inlet side and 4 @ 9mm dia on the exhaust side) are doubtless that size for good reason
to regulate the flow from block to head along the length of the engine.
quote:
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?
@ashg:
I suspected air locks, but was hoping that after a few operating cycles they would dissipate - not so.
Header tank is the highest point; it's currently on brackets at the back end of the cam box with about 1/2 inch clearance to the bonnet.
It's a Sierra tank.
It's always done it - it was SVA'd back in Feb/March and been OTR since early April. I've never done more than 8 or ten miles at a
time, but it gets to boiling (and temp gauge off scale) after about 5 or 6 miles.
Ticking over it just about holds its own; the longest I've done this is about 15 minutes only - enough for the fan to switch on, cool the rad
contents, and switch off again. Gauge reached about 2/3 in so doing.
quote:
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.
@austin man:
I couldn't fix on a 'most likely' reason for the overheating and ended up with sufficient doubts of the head gasket that I had to
take the head off. Glad I did now, even if proving that it was OK - otherwise I'd have continued to have doubts about it.
quote:
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.
@Steve:
I have recently re-plumbed the whole system with no change. Previously I had an Escort single row rad and an overflow bottle; now I have a Polo rad
and remote header tank tee'd into the bottom hose - see the pics in my archive...I'll take a look at Flakmonkey's.
Thanks for your responses, guys!
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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