Scored Pistons on remanned engine!

[kenpoed]

Per my prior posts, my Honda accord v6 was clicking like crazy and after valve adjustments etc, nobody could figure it out.

The engine shop tore it back down and found the top 3 pistons (bottom 3 were fine) were scored. They are now being replaced.

What would cause this? From what I understand it is either lack of lubrication or improper install. But why would only 3 be bad and not all of them?

 

[spasm3]

Improper piston to bore clearance would do it.

 

[The_Eric]

Originally Posted By: spasm3
Improper piston to bore clearance would do it.


This.

A very distant second would be that they forgot to lube the bore when they built it.

A piston takes very little oil to keep it happy, so when the engine is running, it's got lube.

 

[Trav]

It could be a lot of things any one of them would be nothing more than a guess.
It wasn't built right thats clear. We don't know if it was bored or just honed, new pistons?
did they check the piston to bore clearance with inside and outside micrometers?

No offense but it sounds like someone did this that didn't know what they are doing.
Did this engine over heat? When you rebuild an engine you take the bore measurement, out of round and taper and other measurements to qualify the block as straight and rebuildable, only then perform the machine work.
Then can you can check the ring end gap and fit the rings and pistons.


If any out of round or taper of the bore wasn't corrected or the pistons are not fit properly it will happen again.

 

[ARCOgraphite]

Maybe they put the pistons in 180 off as I stated earlier. Also could be bore match was not correct - but that would be all 6 unless the parts are all over the place in sizeing

 

[Doog]

Originally Posted By: The_Eric

A very distant second would be that they forgot to lube the bore when they built it.



This is my guess since the 3 top ones are scored. The builder tech simply forgot to smear some assembly lube (or even 20w50 oil) in the bore and tapped 3 of them in there dry. First start and zama scored pistons. The chance that those 3 in a line would be the wrong bore size would be limited unless the guy drinks his lunch.

 

[jrustles]

Could be caused by uneven temperature regulation between the banks of cylinders. Good thing you got the work approved, most honda engines are slappers, usually people call it an aesthetic nuisance and leave it alone.

 

[Trav]

Thats where i was going with the overheating. I think this is the one that overheated but i may be wrong.
In any case the Honda V6 is known for running hotter on one bank if this is an iVTEC.
I am thinking the greater bore distortion on that bank but who knows.

I cant imaging them trying to rebuild the engine in the car so the guy would have to be on smoking something to forget lube on one whole bank or not know which way front is by the arrow or a mark.
Stranger things have happened i guess. I can see this turning into another missing plane thread.

 

[brages]

Does this engine have VCM?

 

[Vikas]

shouldn't there be plenty of intact V6 engines on the recycle market? in almost all Honda V6, engine lasts way longer than the transmission!

 

[kenpoed]

Not making this up. Finally got the car back today, engine purred. Ran great for 50 miles, then at around 30 mph a loud clicking like a belt was off and bang, no power, towed again. Felt like a timing belt coming off.

I can't get this car running even to sell it.

 

[spasm3]

You may need a new engine shop, and or the installing mechanic!!

 

[Donald]

How big a shop is this? Did they buy a rebuilt engine or rebuild it themselves? Its time to have a serious talk with the owner and say this has got to be the last problem or you want a full refund.

The large companies like Jasper (and others) have expensive high tech equipment that a smaller shop could not afford. And they get to pick and choose which block to rebuild vs rebuilding your block.

 

[jrustles]

Originally Posted By: kenpoed
Not making this up. Finally got the car back today, engine purred. Ran great for 50 miles, then at around 30 mph a loud clicking like a belt was off and bang, no power, towed again. Felt like a timing belt coming off.

I can't get this car running even to sell it.


Do you have any indication of the quality of work that this engine shop does? Perhaps an oversight on the timing belt tensioner.

 

[kenpoed]

Reputable engine shop but it has been a mess. Tried goin the jasper route but they don't carry this engine.

Imam wondering how much valve damage is done at 40mph when the timing belt slides off......

 

[kenpoed]

Timing tensioner caused the original belt problem. Ironically I replaced the belt and water pump 20k ago but was unaware they did not change the tensioner at the same time.

I do wonder if aftermarket parts caused so many issues

 

[Donald]

Originally Posted By: kenpoed
Reputable engine shop but it has been a mess. Tried goin the jasper route but they don't carry this engine.

Imam wondering how much valve damage is done at 40mph when the timing belt slides off......


Does RockAuto carry this engine? I got one for my Jeep from them. It was a Marshall reman engine.

 

[jrustles]

Originally Posted By: kenpoed
Timing tensioner caused the original belt problem. Ironically I replaced the belt and water pump 20k ago but was unaware they did not change the tensioner at the same time.

I do wonder if aftermarket parts caused so many issues


Figures. If you do the TBT job yourself, be careful that if you ever need to 'compress' the shaft of the tensioner for installation (if it's not brand new and locked down with the pin already) that you compress it very slowly and gradually so as not to damage the hydraulic piston/cylinder inside of it. If the shop does it, give them a friendly reminder.

 

[cptbarkey]

oh man, what a bad story. i hope things work out.

 

[Trav]

Originally Posted By: kenpoed
Reputable engine shop but it has been a mess. Tried goin the jasper route but they don't carry this engine.

Imam wondering how much valve damage is done at 40mph when the timing belt slides off......


It is an interference engine according to the timing belt manufacturers listings.
Sorry to say that means considerable and expensive destruction. What a terrible ordeal.