MautoK
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| posted on 9/6/09 at 02:15 PM |
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Overheating update
L&G,
Update: I just did the following:
Cold engine + squirt of oil in each cylinder + choke held open + throttle closed (in know it should be open, but...)
Compression test: 157 / 152 / 154 / 160
Plugs back in, drove about 2 miles round the block. Engine just on the verge of boiling  + no fan
Plugs out; choke open, throttle closed as before
Compression test: 145 / 145 / 148 / 110
When I CT'd #4, it got up to 105 psi after about 5 strokes then the gauge crept upwards about 1-2 psi on each successive stroke. The others came
up to their readings in about 5 strokes and stabilised, as you'd expect.
Diagnostic caps on - what do we think of that? 
Cheers,
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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DarrenW
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| posted on 9/6/09 at 02:44 PM |
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It certainly indicates 4 might be a problem, im just trying to think if owt else other than a crack would cause it. Is head in good nick? Could it be
a valve not seating well?
I would have thought if there is a crack then you would have either oil in the water or combustion gasses present in the water. Isnt there a test kit
for testing the latter? Are you losing any water? Have you defo ruled out all of the simple stuff first?
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GrumpyOne
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| posted on 9/6/09 at 02:51 PM |
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Sticky valve?
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Guinness
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| posted on 9/6/09 at 03:02 PM |
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So you are getting equal (ish) compression when cold, but when everything is warmed up (and expanded) you are getting worse compression across the
board? Combine that with the drop on no 4 and it doesn't sound great.
I'd be looking at sticking another pinto in and enjoying the summer.
Mike
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DarrenW
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| posted on 9/6/09 at 03:05 PM |
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quote:
Originally posted by Guinness
I'd be looking at sticking another pinto in and enjoying the summer.
Mike
Can i just suggest you take the current one out first though otherwise nosecone may scratch tarmac allegedly
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Guinness
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| posted on 9/6/09 at 03:09 PM |
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quote:
Originally posted by DarrenW
quote:
Originally posted by Guinness
I'd be looking at sticking another pinto in and enjoying the summer.
Mike
Can i just suggest you take the current one out first though otherwise nosecone may scratch tarmac allegedly
A twinto?
Mike
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DarrenW
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| posted on 9/6/09 at 03:11 PM |
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Can you just imagine a twin engined pinto car. 200bhp, 4wd, 50bhp/tonne
Sorry for leading thread off on a tangent. Back to original topic...................
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02GF74
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| posted on 9/6/09 at 03:26 PM |
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you took the plugs out when doing both tests? & thottle wide open?
did you squirt oil in the warm test?
can you repeat as before, cold and hot, both wihtout a squrit of oil and again with - so int totla 4 tests.
let's rule out any testing inconsistencies before we diagnose.
what does plug 4 look like? If water is getting into that cylinder, the plug would be spotless a la steam cleaning.
how do all the plugs compare?
what is history of head/block?
have you take head apart and do anmy work on it?
can you remove rocker cover and look at valves as you tunr over engine by hand?
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flak monkey
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| posted on 9/6/09 at 03:34 PM |
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There is certainly nothing wrong with your cold test, the hot one is slightly worrying though.
It could be something as simple as a sticky valve, but generally you get virtually zero comepression then.
It could be a cracked head or block, but it would be highly unusual if it is as the pinto is incredibly over engineered.
More likely to be a head gasket issue I would say and its the excess pressure escaping into the cooling system causing the water to bubble up. I would
be suprised if it overheated within a couple of miles. It takes a good 5-8miles for mine to even get to the point where the stat is opening.
Cheers,
David
Sera
http://www.motosera.com
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adithorp
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| posted on 9/6/09 at 03:52 PM |
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Either...
Cracked head...
or...
Cylinderhead gasket.
Sounds like the trouble is just starting and therefore not all the usual symptoms are present yet (steam cleaned plugs, etc) and only aparent once
things have expanded a bit with heat. Compression gases in water will be causing the overheating and low compression, but not severe enough to cause
instant overheating or water getting back to the cylinder...YET. Give it time and all will become clear or take it off now and have it pressure
tested.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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britishtrident
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| posted on 9/6/09 at 04:09 PM |
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Don't jump to conclusion about head gaskets ---
The compression test results indicate the piston rings are totally gubbed on #4 cylinder, and the rest of the rings aren't great but no worse
than you might expect on a high mileage 1960s designed engine.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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omega0684
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| posted on 9/6/09 at 04:19 PM |
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^^^^^ this is what i was thinking as john has just replaced the head gasket.
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flak monkey
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| posted on 9/6/09 at 04:23 PM |
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quote:
Originally posted by britishtrident
Don't jump to conclusion about head gaskets ---
The compression test results indicate the piston rings are totally gubbed on #4 cylinder, and the rest of the rings aren't great but no worse
than you might expect on a high mileage 1960s designed engine.
That could be the case, but it wouldnt explain the overheating would it?
Sera
http://www.motosera.com
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adithorp
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| posted on 9/6/09 at 04:45 PM |
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quote:
Originally posted by omega0684
^^^^^ this is what i was thinking as john has just replaced the head gasket.
Why, was it overheating then? Did you have the head pressure tested?
BT could be right (isn't he always  ) but that wouldn't explain the overheating. Then again I've spent many hours chasing a fault
with 2 symptoms or more, only to find it was 2 unrelated problems.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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BenB
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| posted on 9/6/09 at 04:59 PM |
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Can you get a local garage to stick their CO meter into the radiator filler nozzle to see if you've got CO in the coolant??? Might r/o head
gasket failure (either that or that fancy super duper liquid test kit that goes blue)
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MikeRJ
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| posted on 9/6/09 at 05:42 PM |
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I presume you have double checked the valve clearances? If they are too tight the valves may not be closing fully with a hot engine.
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britishtrident
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| posted on 9/6/09 at 06:03 PM |
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Don't confuse cause and effect over heating causes knackered rings --- rings get to hot which effectively anneals them and they loose spring
tension.
Engine needs replaced or rebuilt anyway.
Original cause of over heating will likely be one of the two causes in one of my earlier posts.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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MautoK
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| posted on 9/6/09 at 08:49 PM |
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OK guys, thanks for your responses.
Here's my mega-answer
First a summary of the problem and then engine details:
Basic problem is that the engine boils after about 3 miles gentle driving or about 12 minutes idling.
When it boils there is a visible stream of bubbles into the header tank - they come up the 8mm pipe that connects the radiator bleed and 'stat
housing bleed to the header overflow stub.
Engine is standard 2L Pinto with 205 block of unknown provenance - it came with the donor (believed to have been transplanted from a Granada).
I've cleaned it externally, new cam belt, new valve stem seals (head on) and recently new head gasket (+bolts) and thermostat. Shortened sump
and pickup.
Observations: No faults found; valves all free in guides. Head and block mating surfaces looked good with no evident flaws; old gasket had no damage
and was uniform all over.
No evidence of scratches in bores, light to moderate carbon deposits on piston crowns and combustion chambers.
Plugs today are uniform in appearance - done about 50 miles - and look like new with no pitting. Centre electrode & insulator are clean, earth
electrode is pale beige.
Cooling system (all new parts except engine & header tank):
Polo rad, Sierra header tank.
Top hose: 'stat to rad upper;
Bottom hose: rad lower to pump includes T-piece for 15mm hose to header;
Inlet manifold looped to water pump small stub;
Rad bleed teed to 'stat housing bleed and on to header tank overflow.
Baffles fitted between radiator and nosecone.
After running the engine today and doing a hot compression test, I waited a couple of hours and retested:
151 / 148 / 150 / 128
A squirt of oil into each cylinder gave:
156 / 149 / 156 / 137
As a reminder, the earlier figures were:
Cold + squirt of oil: 157 / 152 / 154 / 160
Hot: 145 / 145 / 148 / 110
For all the tests, the throttle was closed, choke open. I know throttle should be open, but the conditions were the same each time.
So, yes, something is awry with #4 but it 'recovers' partly as the engine cools down. Taking the temperature dependence and bubbles into
account, I'm more and more convinced of a crack...
I would say a sticky valve is unlikely - they were all nice and free when I did the stem seals - and as Mr flak says I'd expect near zero
comp.
The conclusion has to be that the engine is 'gordoned'.
Anyway, it looks as if I've sourced another engine so we'll see how it goes over the next few days...
Many thanks for all your help and comments, guys.
Will let you know how I get on.
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 9/6/09 at 09:08 PM |
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Definition of 'gordoned':
Giving the outward appearance of normal functioning while internally there are cracks developing, with much seething and discord, getting worse as the
temperature rises; i.e. knacked.
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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