ChrisL
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| posted on 5/1/20 at 06:18 PM |
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Overheated Zetec = compression loss
Whilst get the SC conversion done I've managed to overheat the engine, massively as I didn't notice a huge split in a hose and when
checking the header when cold there was still some water in it, at the bottom of the tank. Was too busy trying to tune and drive to look at the temp
gauge, so here we are but at least it explains the oil vapour coming out of the breather!!
I've done a cold compression test and the results don't look good:
This is in PSI, I checked twice!
Cyl Dry Wet
1 25 45
2 10 50
3 25 50
4 60 135
So now what to do? Is it worth getting the engine up to temp and re-run the tests? is it worth attempting to salvage if so is it just new rings? What
would cause issues on the head?
I've bought an endoscope to see if I can find any bore damage, before taking the head off.
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cliftyhanger
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| posted on 5/1/20 at 06:38 PM |
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Those figures are a disaster.
Th head needs to be off, checked that isn't bent like a banana or worse, pistons out to check the rings....
You may be lucky and "just" need a hone/rings and head skim. But if you stumble across a good engine I would be buying it.
The figures imply the pistons are not holed, or a wet test would have made no difference.
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steve m
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| posted on 5/1/20 at 06:39 PM |
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From experience with a 1700 crossflow, that I seriously overheated it until it seized, on the way back from an Skcc run 
The block and head were used again, but the crank, rods, pistons, piston rings and valves were all binned
If your lucky, and it didn't seize, then I would rebuild it, with new rings and bearings, assuming everything else comes with in tolerances
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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steve m
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| posted on 5/1/20 at 06:41 PM |
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The compression figures were done with "wide open throttle" ???
as if not the figures are usless
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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britishtrident
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| posted on 5/1/20 at 08:41 PM |
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As above use wide open throttle and all spark plugs removed. Soak some Redex down the bores for a few days before the next test.
Severe overheat damage to piston rings rarely shows up immediately usuall months latterbut most times there is no issue.
[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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ChrisL
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| posted on 6/1/20 at 10:51 AM |
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Thanks for the replies, so the orifginal figure were not WOT so I've done them again, I'd consider the first set as wet as I could still
see the oil down the bores. I started the engine and let it idle for a about 5 mins so the water temp was just starting to rise. Not fully up to temp
but I've got fussy neighbours!
Cyl Wet Warm
1 40 25
2 20 15
3 65 40
4 135 80
Quite surprised that the pressure held went down when the engine was warm!
Will have look with an endoscope when it arrives and take the head off at the weekend
Cheers
Chris
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MikeRJ
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| posted on 6/1/20 at 12:41 PM |
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Serious overheating will soften the crown and the lands of the pistons, which can then smear and trap the rings, even if a full seizure didn't
occur. The rings themselves can also lose their temper which prevents them sealing well. Pistons exposed to such high temperatures should no be
re-used.
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big_wasa
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| posted on 6/1/20 at 01:35 PM |
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My old man cooked a zetec until the valve seats dropped.
Zetec's are getting harder to get but I would still get another.
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steve m
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| posted on 6/1/20 at 02:18 PM |
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The fourth cylinder was doing all the work, to keep the other three spinning according to
your compression readings!
Also, as Mike said, my piston ring gap on the pistons, had broken up, so the rings had no were to sit, so all four were scrapped
I did use the engine again, but it was a FULL rebuild with known parts
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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snapper
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| posted on 6/1/20 at 03:10 PM |
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I recon it’s a warped head.
You can skim a warped head but it’s not the ideal way to go as you will increase compression in the chambers in an uneven fashion, it will still run
ok but in warping a head is a skilled (and expensive) job.
Best to pull the head off and check head and block for warping.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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ChrisL
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| posted on 7/1/20 at 06:12 AM |
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Cheers chaps,
Just bought a new engine with a reported 80K on it. When I get time I'll take the old one apart to see what caused the issue. Just wondering if
it's worth doing anything to the new one before I fit it? I'm planning on putting in ARP corned bolts atm.
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steve m
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| posted on 7/1/20 at 06:58 AM |
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Put brand new hoses on ?
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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ChrisL
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| posted on 7/1/20 at 08:58 AM |
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haha, yes probably a good idea!
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procomp
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| posted on 8/1/20 at 03:59 PM |
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Anything over 107deg warps the head.
we just had a head skimmed by 4tho to correct a warped head after a 110deg moment when auxiliary belt came off at Oulton with 2 laps to go.
we also had new rings fitted i should mention also.
Cheers Matt
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ChrisL
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| posted on 8/1/20 at 05:00 PM |
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Ahh that would fit with it reaching 114 degrees!
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cliftyhanger
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| posted on 8/1/20 at 05:45 PM |
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A new timing belt would be wise...
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ChrisL
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| posted on 8/1/20 at 08:08 PM |
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On the list so far:
Timing belt
Water pump
Spigot bearing
Plugs
Oil and water flushes
Cheers
Chris
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ChrisL
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| posted on 11/4/20 at 10:25 AM |
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By way of an update, new engine is in but can't get oil pressure I've primed it and tested with a manual guage as well as the sender still
no joy and beginning to suspect that may be the reason the car was scrapped. Also noted that the crank front oil seal is weeping so...
I've started stripping the old engine, with a bit of help from Mr Haynes. So far the bores look good, there's still evidence of the cross
hatching. The head is a little out of true, I've not looked up the specs but measuring from corner to corner across the head the a gap of 0.18mm
in the centre, no idea if that's good or bad but I did read of a chap you had 3mm which is what I was expecting. The camshafts all look ok no
scoring or shiny spots but will measure before re fitting.
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ChrisL
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| posted on 23/4/20 at 09:03 AM |
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And the winner is....
Overboosting, seems I got up to over 12 psi of boost and that was enough to smash the pistons (thanks to my knowledge friends who looked at the pics
and told me the cause!)
 
Description
and
 
Description
It seems I made some assumptions around the pulley sizes, so wasn't running what I thought/bought!! Oh well lesson learnt!
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