Super rough running - cause?
Orig. Posting Date | User Name | Edit Date |
Jun 19, 2019 03:25PM | malsal | |
Jun 19, 2019 01:54PM | onetim | Edited: Jun 19, 2019 02:03PM |
Jun 19, 2019 01:28PM | spectre1275 | |
May 20, 2019 09:13PM | spectre1275 | |
May 9, 2019 10:01AM | malsal | Edited: May 21, 2019 06:55AM |
May 9, 2019 07:51AM | spectre1275 | |
May 9, 2019 07:47AM | malsal | Edited: May 21, 2019 06:56AM |
May 8, 2019 08:50AM | dklawson | |
May 8, 2019 05:56AM | spectre1275 | |
May 8, 2019 04:35AM | dklawson | |
May 8, 2019 04:28AM | Willie_B | |
May 7, 2019 08:50PM | spectre1275 | |
May 7, 2019 06:59PM | spectre1275 | |
Apr 15, 2019 04:21PM | scooperman | |
Apr 15, 2019 12:08PM | spectre1275 | |
Apr 12, 2019 11:57AM | dklawson | |
Apr 11, 2019 10:56AM | 850mini | |
Apr 11, 2019 09:49AM | scottwkurth | |
Apr 11, 2019 09:26AM | swindrum | |
Apr 11, 2019 05:15AM | Dan Moffet |
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If in doubt, flat out. Colin Mc Rae MBE 1968-2007.
Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.
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Glad to hear you got it running nicely.
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Head gasket replaced, new thermostat, bypass hose, and now am sporting 175 of compression at each cylinder and an overheating problem I had before the head gasket issue (as indicated by the gauge) seems to be resolved. Oil pressure is running about 85 (pressure of the oil pressure relief valve I believe) when starting and at speed, but no leeks, and it's only got 600 or so miles on it.
All good! So happy it wasn't a more serious issue like a cracked block or head.
On to the long list of other things to fix on it.
Scott
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Getting closer to get it all back together. Block and head are nice and flat, head cleaned up, put on and torqued down.
On to flushing the coolant, changing the oil and doing a few other finicky things in the engine bay, then adjust valves and timing, and start it up.
Will keep you posted!
Scott
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Just follow the torque wrench settings and sequence and re torque after 50 to 100 miles i then re check at 1000 miles and adjust the valves if needed.
If in doubt, flat out. Colin Mc Rae MBE 1968-2007.
Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.
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Will fit the gasket dry as well, run it in with just water as coolant, and then add water wetter.
Thanks all!
Scott
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Scott
I would not use any sealant on the head gasket, fit it dry.
If in doubt, flat out. Colin Mc Rae MBE 1968-2007.
Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.
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Scott
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UNC UNF
1/4-20 1/4-28
5/16-18 5/16-24
3/8-16 3/8-24
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https://www.summitracing.com/parts/sum-900200/overview/
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Scott
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My son and I pulled the head after confirming that cylinder 3 compression was South of 100, and 4 was on it's way at 120.
We undid the head nuts, pulled the pushrods (keeping all in order), but late at night were stymied by the exhaust manifold, so closed up for the night. We did learn that the rear nuts were significantly tighter than the front (though I failed to check torque before pulling them off, to see which ones were too loose and/or too tight)
Next day we managed to get the manifolds off, and pulled the head. It may be that overnight with the head loose oil leaked between the block and head, but the gasket was pretty shiny with oil. See attached picks - we saw that the valves looked relatively buff and dry apart from the large valves in cylinders 3 & 4 (with 3 being much more sooty, even wet). In the pic the rough edge you may see on the valve in cylinder 4 is just dry debris from pulling the head and whisking a finger around the valves to see if it was wet or dry).
Any thoughts on the interesting patterns seen on the head and block? Looks like moisture got in there somehow, either from oil or water.
No scoring on the cylinder walls (still see the marks from the honing, as this engine only has about 1,000 miles on it), and all 4 plugs are uniform and grey. No noises from the water pump, and oil pressure was high if anything, so not going to replace either of those.
I've got a new gasket coming, along with thermostat & gasket, valve cover gasket, manifold gasket and bypass hose.
Looks to me like I just didn't re-torque the head down after a few hundred miles, or didn't have it right to begin with, and got lucky with not driving it much/hard to damage anything. Anyone see something else I should investigate?
Planning to whack it together, perhaps using copper coat on the head gasket, change the oil/filter, coolant and gas filter, and see how she runs.
QUESTION: I'd like to chase the head stud threads in the block - what's the correct pitch/thread to get?
Scott
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Cylinder 1: 135
Cyl 2: 115
Cyl 3: 170
Cyl 4: 165
May do a wet test as well, but gasket is very suspicious with two cylinders experiencing low numbers.
The engine was rebuilt less than 2,000 miles ago, oil changed 3 times since, pulled and drove well until last week.
Next steps:
Check head studs for correct torque
Check exhaust and intake manifold bolts for tightness
Compression test again, and perhaps do a wet test
Pull the head to see what's what...
Scott
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Last week on the way home, it started losing power, and sounding like it was running on 3 cylinders.
I never did find out what the #$%#@ went through the engine, but there appear to be some small pits on the piston head. I haven't had time to get in there with my borescope for a better view. It's on the list...
Scott | 1963 Austin Cooper | 2003 MINI Cooper S | 2018 MINI Cooper 4-door
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If it happened all of the sudden, it could mean a head gasket. Pop all of the plugs out and do a compression check. I have has HG failures that didn't affect cooling. If the gasket lets go between #2 and #3 cylinders, the oil and coolant can stay where it belongs, but have no compression on those two cylinders.
My experience is that coils are pretty bulletproof, unless you get a Lucas Sport Coil, those can be pretty crappy. A known good coil is and easy test though.
Sean Windrum
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If timing is badly retarded, idle can still be smooth, though you won't get good combustion and thre's be loss of power. Causes could be the timing has slipped or the advance system isn't working.
It could also be that the base timing is OK but the vacuum advance has failed (e.g. broken spring) in the full on position. Idle would be OK because the mechanical (or electronic) advance curve is not in effect. When you increase rpm, the curve might be adding to the vacuum advance resulting in excessive advance and loss of power and rough running - vacuum advance is supposed to fall back as the throttle opens.
.
"Hang on a minute lads....I've got a great idea."
Found 23 Messages