Looking for a reference and pictures on bearing, ring, piston wear.
What's considered normal, excessive, etc.
Not looking to 'save' bearings or rings - going to replace - but would like to better understand their condition.
Bearing, Ring, and Piston wear analysis
Looking for a reference and pictures on bearing, ring, piston wear.
What's considered normal, excessive, etc.
Not looking to 'save' bearings or rings - going to replace - but would like to better understand their condition.
I look for just how much "shiny" area there is on the bearings. More shiny = more wear. Also look for any grooves where some foreign matter might have found it's way into the oil. You could plastigage them, but like you said since you hvae it apart why not replace them.
On rings I do a leakdown before teardown. More leakdown to the crankcase = more ring wear in the absence of cylinder or piston damage. Could also check end gaps.
Pistons, If you measured them before assembly, remeasure. Obvious scuffs also = wear.
Just MHO.
I'll measure everything as I assemble. Never opened this engine before.
Ran fine (but low power).
I had done a leak down in the past and it was acceptable.
Had a big oil loss last year and seem to tighten as I pulled into the pits.
Pulled and replaced the motor to make the next race.
Been sitting ever since. Bottom end was still dripping in oil. So that should bode well for the crank.
Pulled 1 piston and the journal looks fine. Maybe the bearings got really hot - not sure.
Some simple stuff.
The top ring should have a .015" gap. Take that ring and measure the gap at different places up and down the cylinder.
You want to know how much wear is in the bore.
Piston to Cylinder wall clearance should be about maxed at .005"
Torque the rods with the bearings in them and measure inside diameter and roundness.
Check that against the crank journals.
Oil starvation might appear first on the cam bearings.
Many times with dry sump systems you can loose a good amount of oil but still have pressure to the bearings. (still not a good thing)
It might just need new rings and bearings and be ready to go. If it got real hot, I'd change the valve springs.
Head was wet with oil too. I'm not sure it got starved, but something went wrong
Top ring gap is .016. I measured the bore in 3 places (bottom, middle, top) and got 90.85, 90.87, and 90.85.
As the ring wears it also contributes to the increase in gap, correct?
Rings are tight in the pistons. Comp 1 has about a .005 gap.
The compression ring edge looks really rough to me.
The wear in the cyl and on the skirts looks normal to me. Is that a fair assessement?
The rod bearings I'm unsure of... I don't see too much shiny but the patterns look uneven.
Here are some pics:
Attachment 86106Attachment 86105Attachment 86104Attachment 86101Attachment 86102Attachment 86103
So, if it got hot and weakened the springs, could that cause a loss of power with normal leak down and no obvious valve float?
Bearings look like oil starvation. Check the centre main as that normally gets it first due to the way that the oil is distributed to the bearings in a kent engine. The front cam bearing also takes an hit as carries the oil to the head.
https://www.knowyourparts.com/techni...earing-damage/
https://www.agkits.com/bearing-failure-analysis.aspx
Piston ring is knackered, should have a bright wear line on it depending on the original type. Most middle rings are tapered so the wear should be at the bottom part of the ring face.
Bore and Piston looks like they have started to seize/tighten up. A hone may sort out the bore and will be needed for new rings anyway.
Bearings
Mahle has a good site on bearing problems.
This is a Pinto. I believe the oil moves the same way. I'll pull the crank tonight to get a look at the mains.Originally Posted by kevskisps
Thanks for the references. Any idea why the ring would look that way?
An obvious source of power loss.
Do you think the pistons are okay. Other than cleaning any other treatment?
Piston
Number four? My guess is the #4 runs hot because of the cooling design.
I'd buy new pistons and carefully check those bores for out of round.
#1. I'll pull them all and post the pictures.
Looking at the Mahle guide ( https://www.mahle-aftermarket.com/na...eanalysisguide )
the bearings look somewhere between oil starved and contaminated. With the ring looking like it does, blow-by contamination is a possibility.
Are you re-building this engine to secure your position as a backmaker?
That .005" ring groove clearance should be .002" or less. These pistons should be replaced.
Brian
I've already got that position secured
Actually it's looking like I should just sell everything and quit. I'm out of my league $$ wise.
I tried to have fun but it's not working out.
Hope so, I need someone to run with
So... I would say, "Bless your stars!" Lucky Dog... you turned it off before it became a boat anchor.
Bearings are shot to hell. Pistons, close behind. If the rods are turning blue, they are junk also.
Bores need to be measured to see if they are tight enough, and round enough for new pistons.
I'd have a good machine shop polish the crank and measure.
You said you had good compression... was that with a compression guage held in the plug hole?
Or, was it a real leakdown test?
I don't believe the ring in the picture would support a 95% or better leakdown. Just saying.
Are you racing on sandy tracks with no air cleaner?
I was wondering if the block was properly cleaned during the last rebuild... of if you were using a Wal-Mart oil filter.
The oil pump needs a replace or careful rebuild.
BBR
Assuming you have a spin-on oil filter ?? , remove it drain oil in a small pan then cut the filter open.....either using a dedicated filter cutter or Wiss shears and lay out the filter media on a clean paper or white cardboard sheet. Then you can see the trash that is imbedded in the media.
Either you had a failed oil pump causing oil starvation or hard detonation and high heat then detonation and then starvation, causing destruction of parts....it shows on all your parts.
As Frog says.....lot of paper weights..... good luck.
JB
The trash goes everywhere....
Make sure you clean every possible part of your oiling system. Pull all the hoses and clean them or replace them if you can visually inspect them. Pull the oil tank, strip it, and have cleaned in solvent and then ultrasonically cleaned.
"Do-Overs" suck.
Regards,
Dan
“Racing makes heroin addiction look like a vague wish for something salty.” -Peter Egan
Add in flushing the oil passages in the block.
Jake's book on the Kent recommends removing all of the gallery plugs and using rifle bore cleaning brushes with solvent and then soap and water. Amazing the grime that comes out.
“Racing makes heroin addiction look like a vague wish for something salty.” -Peter Egan
I bought a gun cleaning kit (and a kiddie pool) on one trip to Walmart.
I think the kit was $12. Brushes for 12ga to 22s.
Don't forget the turkey baster, HF solvent sprayer, bottle type brushes and Walmart purple cleaner.
Considering the molasses bath too.
Hello Paul,
Molasses bath? Usually only for rust.
Contact Tony Ingram for help. My son found him very helpful and reasonable. http://www.lotus7.com/Home.html
Regards,
Dan
“Racing makes heroin addiction look like a vague wish for something salty.” -Peter Egan
Want to clean the water passages. It's not as bad as I thought it would be...
I'll contact Tony.
Finish tearing it down today.
The main bearings look okay. No discoloring, etc.
Attachment 86163
The crank also looks pretty good:
Attachment 86165Attachment 86164
Rod bearings 1 & 2
Attachment 86166
and 3 & 4
Attachment 86167
So it seems 1 & 4 got starved. Obviously need to look closely and the crank passages.
And the Aux Shaft bearing looks like someone installed it with a screwdriver and hammer:
Attachment 86169Attachment 86168
Regarding loss of power:
Other than rough rings, #4 had a broken 2 ring.
That looks like an overheating problem to me not oil pressure failure.Finish tearing it down today.
The main bearings look okay. No discoloring, etc.
The crank also looks pretty good:
Rod bearings 1 & 2
and 3 & 4
So it seems 1 & 4 got starved. Obviously need to look closely and the crank passages.
And the Aux Shaft bearing looks like someone installed it with a screwdriver and hammer:
Regarding loss of power:
Other than rough rings, #4 had a broken 2 ring.
Engine almost seized and all the swarf from the pistons went through the oil system.
There is no 'blueing' of rods or crank signifying loss of pressure.
Replacing ALL bearings, thorough (I mean THOROUGH) cleaning of the block and head, ALL oil lines too. Hone the bore, polish the crank, it may be saveable in my opinion. New pistons and rings of course (need to check bore size for correct replacement size).
Last edited by Keith Robinson; 07.05.19 at 4:06 PM.
Definitely needs a thorough clean up and polish of the crank be a crank shop where they polish it in a machine that takes the high spots down.
Lucky it did not go bang. Glad you shut it down in time.
Definitely needs a thorough clean up and polish of the crank be a crank shop where they polish it in a machine that takes the high spots down.
Lucky it did not go bang. Glad you shut it down in time.
Is the head still straight?
TBD. Just doing some initial measurements on the head.
Just off the phone with the guy looking over the bottom end.
Block needs sleeves. It's nice and wavy. As I said P4 had a broken ring and it showed in the bore.
Crank need a grind. Mains out of round by .0007 but oddly the bearings don't really reflect that.
I think the bearings were quick-swapped in to make it run.
Flip the motor and R&R bearings without even pulling the head.
That would account for the dirt and several other discoveries.
I'll know more on Monday when he has a look at the rods.
Sorry about the sleeves
Maybe be stating the obvious but, go through the oil pump now, it is the heart of the engine and I have seen a lot of rebuilds assembled without a rebuilt pump only to have the engine fail quite quickly after. Check the rotor to housing clearances and the casing for scoring and damage. Sorry but this adds to the parts list.
Planning on sending it for service.
All of this thread is on my original (I call Blue) engine. I have a second (Black) engine I just tore down today that was running the same pump - but also had an oil starvation problem. As I started to take it apart, I found the pulley on the jackshaft had sheared it's pin.
Nothing good there either. Everyone likes to see a train wreck so I'll post pictures of it later.
So, my second engine "Black" had the pin on the jack shaft fall out (actually into the slot it sits) allowing the pulley to spin.
I don't know how long it takes to create this sort of damage. Mains seemed to not get starved.
Rod bearings shredded and fused to the journal.
Looks like the rods are toast. Crank probably unless the bearing material can be removed and ground.
Attachment 86184Attachment 86183Attachment 86187Attachment 86186Attachment 86185
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