Two weeks ago we mede a small round and then suddenly there was a loud noise and the engine stops. I disassembled the engine and found the following damage:
1 cylinder the piston have deep scratches
2 cylinder the same
3+4 cylinder the piston have not so deep scratches
Any ideas what the reason is?
The next step i measured the piston ring clearance and it was 1,6 mm (0,06 inch).
The clearance between the piston and the cylinder is 0,6 mm (0,023 inch).
Thanks for all ideas or explanations.
Kind regards
Michael Velling
The pistons are too tight.
Not enough clearance.
You measure the clearance at the bottom of the skirt.
The ring end gap is a little big but no problem.
The scuffed pistons would not make the engine stop with a bang, Michael. What else did you find wrong?
Was there enough oil?
I believe those are seize marks, from the pistons super-heating due to lack of cooling. The pistons start to melt and slough off when they were forced to keep moving. Something caused the engine to overheat would be my guess. Water? Oil? Timing?
There was enough oil (4 Liter) and i found nothing other reason for this. Everything is fine..the bearings at the crankshaft and so on. Only this damage and a connection rod on cylinder 2 that is fixed to the piston pin. You cant turn it. Short before the damage we had heard a knock...?
Michael
Ricks, I'm with you on this one per your point on enough oil. Seems a bit odd that all pistons are scuffed. I guess the real question is, reconditioned engine or no, if no: How often does Michael drive the T? Does he check the oil making sure that he saw a consistent stream coming out of the top petcock prior to every excursion? Were there any issues prior to this incident?
If reconditioned/rebuilt the questions are endless starting first with qualified builder or not and how often driven since build and duration of trips. Then the questions really begin.
Did you check if the inside oil line was plugged?
It overheated severely. Could have had the bands adjusted too tight, blocked cooling for some reason, or a blocked oil line.
Was the water frozen in the radiator or did you have a reasonable mix of anti freeze in the coolant? You can overheat a car on a winter day easily if the coolant is not capable of cooling.
Thanks for the first reactions.
The oil line was free (inside and outside).
The oil level is proper (i check it every drive), we drove this year around 2000 km (1300 mls).
The engine was not reconditioned at this parts. We only have made new connecting rods, main bearings in spring 2012.
The water was a mix of 50% water and 50% anti freeze. I took 8 Liter / 2 gallons out there.
A few minutes ago i talked to Toon Boer and send him some more pictures. Here are these pictures from the valves, it seems they are getting to hot...but why?
I think if the bands are adjusted to tight the drums must have some scratches too?
Michael
He says one of the wrist pins is seized up. A seized wrist pin actually can cause the engine to stop with a bang. The other ones were likely very stiff during operation and that is what caused the galling on the cylinder walls. I've seen this a couple times before and I even have an engine in the shop right now with this problem... A MAJOR issue is that many engine builders just put the pistons in without checking (or correcting) the bores for the wrist pin. Many times, the wrist pin bores in the pistons are too tight, the surface finish is not smooth enough, or the bores are the right size but not perfectly aligned (I find this last item to be the most common). I particularly have found this issue with two brands of what many hobbyists consider the "better quality" pistons. It is maybe partially the fault of the manufacturer, but pistons really need to have the wrist pin bore checked and properly adjusted on a piston pin honing machine and that responsibility is the re-builder's.
Looking at the photos I thought of something else that I've seen before that could be a factor... You are not running Aviation Fuel in your engine are you???
"and a connection rod on cylinder 2 that is fixed to the piston pin."
Michael, I think you must mean the piston pin is fixed to the piston? How thick are the pins? Thin pins will distort when clamped, and cause binding.
rdr
Ricks... I have also occasionally found that a connecting rod with a burred bore on the small end seems to slightly distort even a "thick" piston pin". I make a point of precision hone-ing the small end of the connecting rods just to clean up the burrs.
That engine looks like it was red hot before seizing up! My first impression is no coolant passing through the block, causing a loss of oil film.
I have a feeling the radiator was blocked inside or the coolant would have been blown out in clouds of steam, which you would have seen.
Thanks, Adam; never thought of that one.
Michael said that the piston to bore clearance was .023" . I'm somewhat new at this, but isn't that a lot?
schuh
I'm with Adam. We just went through a fairly freshly rebuilt engine that had a seized wrist pin. It had new aluminum pistons. Apparently, like he says, the wrist pins do not come fitted from the manufacturer (I'm not sure why not). The fellow that had the engine said it sounded like something came apart inside the motor. Probably this was from the galling, which caused things to seize up, and then it was real hard to turn over. The pin was stuck in the piston and would not come out. It did come out after putting it in a press. I think I have an engine of my own that is suffering from the same thing. It overheads and occasionally is a little tight when hand cranking.
I think the tight piston pins is probably the problem. I find that as many as two or three piston pins in a set are TOO TIGHT. I talk to some good model T mechanics that say they don't find pins that are too tight, but I do. Years ago The best T mechanic in the country told me to slap a piston in your cupped hand and if the pin does not drop out its TOO TIGHT. The old method of installing a rod and holding the piston horizontally and see if the rod falls down can still be too tight. I think the only safe way to test the pins are to slap it in your hand. If you do not have a hone fixture then take your pistons to a good machinist and have him hone them for you.
Some of the Chinese made pistons sold n the past 5 years were not cam ground so they seize in the bores when hot. Have you checked the pistons to see if they are round? They should not be.
Again, the engine overheated severely, so there must not be any temperature indication or the driver would have stopped prior to the piston pin(s?) seizing in its bore.
I thought I had really scored a deal on this set of hones at the local swap. Turns out to be too large for early Chevy pins, which are 0.85, and T pins, of course.
OK... Retarded timing + Incorrect carburetor setting = Extreme heat. But you would have seen the car boiling over madly, or the plume of steam.
If no steam, then it sounds like low / insufficient cooling. Did it pop a freeze plug and drain its coolant? you had a 50/50 mix of antifreeze/water, so frozen radiator sounds out.
Know what I think? Very first impression - Look at the exhaust valves - all 4 of them. I'd love to see a full color shot of the business end of the spark plugs, but I'd bet they are as blistered as the valves, meaning the air/fuel mix was Too lean. WAY too lean.
Cracked or warped manifold? Carb? Manifold gone loose? Displaced gasket? Something turned that nice even flame into an oxy-gasoline torch inside all 4 cylinders.
That's where I'd start my search. DId someone say AvGas or some other exotic fuel mix (Ethanol or racing fuel) put in by error? That would exacerbate the problem.
OK... Retarded timing + Incorrect carburetor setting = Extreme heat. But you would have seen the car boiling over madly, or the plume of steam.
If no steam, then it sounds like low / insufficient cooling. Did it pop a freeze plug and drain its coolant? you had a 50/50 mix of antifreeze/water, so frozen radiator sounds out.
Know what I think? Very first impression - Look at the exhaust valves - all 4 of them. I'd love to see a full color shot of the business end of the spark plugs, but I'd bet they are as blistered as the valves, meaning the air/fuel mix was Too lean. WAY too lean.
Cracked or warped manifold? Carb? Manifold gone loose? Displaced gasket? Something turned that nice even flame into an oxy-gasoline torch inside all 4 cylinders.
That's where I'd start my search. DId someone say AvGas or some other exotic fuel mix (Ethanol or racing fuel) put in by error? That would exacerbate the problem.
Hi All ; Can it be that the engine was running lean on Gasoline??
Hi Susanne,
no boiling, no steam -just this damage. Maybe your idea with the manifold is the reason. I have screwed them away to adjust the valves and then returned both manifolds with the old gaskets (Glend ring copper). After this procedure (2 weeks before) the engine broke down. How can i understand the problem with the manifold?
Michael
The gland ring copper gaskets are one use only - once they've been compressed, they usually won't reseal, creating air leaks and lean running, and the fuel-air mixture will be like an oxy-acetylene torch, hot enough to melt your pistons and cook your valves.
2 things - ALWAYS use new coppers and glands. They're cheap insurance against this kind of damage. Second, make sure the spaces where the steel glands fit in the lock and intake are clean, as well as the surface of the block and manifold, so the coppers will seal flat! (Oh yeah, part of the reason not to use the flat gaskets is they may also have issues sealing - or the manifolds can shift without the steel glands.)
Oh yeah, make sure the carb is sealed as well. A leak there will be just as bad.
At least the damage wasn't to the lower end as well...
This pattern is typical for an engine that overheated. Look at the color of the valves The carbon has been burned up from the high temps and the scoring is most of the way around the piston skirts from the swelling factor. Also, as the piston swells in the bore and the engine loses power and usually stops dead. This is not cased by a lack of lubrication. I have seen this many times in my engine rebuilding.
I didn't read all of the messages carefully but the issue could be that aluminum pistons must be cam ground as Royce stated and this could be the problem. One of the piston suppliers accidentally let some get out of the shop without being cam ground and there was a lot of trouble from it. Your pistons worked well before you reworked the engine and ring gap can cause an issue but yours are too big and that should not have cause galling. I had an engine look like that one back in 1950 and it had broken rings.
If it ran fine and all you changed were the piston pins, then it was the tight fit that cause the skirt to drag on the cylinder wall. The unsolved issue is that the cylinders and pistons are ridged all the way around as if it had broken rings.
Avgas would not cause any problem. 100LL is approximately 110 octane in automotive R+M divided by 2 testing. It would run no differently than 87 octane unleaded in a Model T.
Royce, is 100 Lotsa' Lead still 2gm/gal?
Bud - the 0.023" clearance is normal at the top ring area of an aluminum piston, that's where it's hottest and will expand the most. Normally the clearance is 0.005" down at the bottom of the piston 90 degrees to the piston pin.
Hi Michael, tough luck Fortunately it's just in time for garage season, so you won't miss any important tours
Perhaps it isn't as bad as it looks.. if the grooves isn't very deep, then a honing tool could perhaps renew the cylinder surfaces for another season of touring?
I've filed off galling marks on pistons and been able to reuse them, it's the rings that does most of the sealing anyway. Just check so the clearances isn't really excessive after some smoothing of the pistons.
Be sure to check that all the rings are free in their grooves - and that the piston pins are free to move in the pistons. If you're holding a piston with a mounted rod pointing straight forward, the rod should be able to fall by its own weight. If it doesn't, the piston pin is too tight and might seize when hot.
Susanne's got the best idea yet on the reason for all this - with new manifold gaskets, the T will hopefully run smooth for next season
Thanks for that answer Roger.
schuh
I think Adam is talking about my engine which is in his shop. One of my pistons looked very much like Michael's pistons. Wrist pin seizure. We had to remove the crankshaft in order to get the piston out. The connecting rod was stuck tight in the piston and it should swing like a bell clapper.
The noise I heard just before the engine seized was like putting ice cubes in a blender. Chop chop chop
I defer to others in regards to the valves looking the way they do.
My valves look like that only slighty darker.
Air leak at manifold connection between #1 and #2 cylinders in combination with too-tight piston pins caused this engine to fail? Anybody that thinks these old engines are bullet-proof and will run without careful attention to detail when repaired need to read this forum regularly for an education....I am learning a lot and appreciate those willing to share their experience (good and bad) with me.
Since there has been pistons sold in recent years without being properly cam ground, perhaps that's one of the combined causes for this seizing? (Aluminum pistons should be machined oval with the smaller diameter along the piston pin - they'll expand along the piston pin and end up approximately round at operating temperature.)
Ralph - no idea. The EPA is trying to force the idea of unleaded AVGAS on the FAA at the behest of the Obama regime. 100LL would be phased out. Cost would be prohibitive, but idiots don't care about consequences do they?
That should finally cause the end of private aircraft ownership entirely.
The EPA (started by Nixon) has supposedly been after 100LL since Reagan was Prez. 80/87 had only 0.5gm lead, but the engine makers went to 100LL with 1.2 to 2gm lead, and the oil companies phased 80/87 out after demand went down enough. 100LL is a safety hazard, especially in planes designed for 80/87, due to plug fouling. I know.
My Corvair with higher performance 1964 engine needed a valve job after running leaded 100/130 for a few tankfuls during the 1979 gas "crisis". I would never run 100LL in a T or any other car designed for unleaded.
Wiki has quite a bit on it: http://en.wikipedia.org/wiki/Aviation_gasoline
Here's a nugget:
"Despite assertions in the media that leaded avgas will be eliminated in the US by 2017 at the latest date, the EPA confirmed in July 2010 that there is no phase-out date and that setting one would be an FAA responsibility as the EPA has no authority over avgas. The FAA administrator stated that regulating lead in avgas is an EPA responsibility, resulting in widespread criticism of both organizations for causing confusion and delaying solutions."
In other words, 100LL is used to scare constituents, increasing membership in AOPA, Friends of Earth, and other such organizations.
Be sure to read the part about Swift Fuel, which is largely acetone.
I'm waiting for Roger to chime in with Sweden's experience with unleaded avgas. .
rdr