Piston Rings Worn Out, Time for a Rebuild

[HanksDeuce]

I bet if he bobbed it there wouldn't be any further engine problems. Less weight to haul around.
[/sarcasm off]

Good luck getting it torn down and fixed.

 

[JasonS]

Maybe yes.... ? I just don't think that 22 gpm is that much, considering the size of our engines. For reference, a stock Chevy-sbc oil pump puts out 18 gpm @ 3000 rpm and the same but with a high vol. pump, will flow more or less what the book says a std. Multifuel pump does. (HDO-30 at 180º @ 2600 rpm)..

The chevy oil flow referenced above is at oil pump speed which is half of the engine speed. In other words, the SBC is spinning at 6k crankshaft rpm.

 

[Wildchild467]

Me too. We checked the compression heigth from wrist pin bore to piston top, and that was the same. So, at least the low compression is not from that. Plus, that would not shoot leak down figures down the drain like they are. He just checked his lawn mower, and the leak down was like 2%......

Yup, K321 Kohler in a 1978 Power King 1614. I love the tractor... mainly because it does not have any blowby.

 

[Wildchild467]

Well we got the heads off the truck tonight. We as in my Dad, 74M35A2 and I. We were hoping to find some head gaskets damaged, leaking, etc... but we didn't find anything. Nothing out of the norm. We didn't find any signs of leaking. The cylinders still have the cross hatch and do not appear glazed at all.

Here is a picture of the sludge I found in the valve covers. I never had this problem before the rebuild. I even changed the oil again after I found the sludge and it did not go away. It only can be antifreeze I guess. Even then we did a cooling system pressure test and the gauge held at 7 PSI. So even if we think the pistons are bad (and who knows at this point) then what explains the sludge?



As you probably know, these are NOS heads. Could they or one be cracked? Has anybody ever had multifuel heads pressure checked? The one breather hole in the rear valve cover was completely plugged by this thin viscosity sludge. If I had to guess, I would guess the problem is with the rear head... but that is just a guess at this point. Everything looked good when we took it apart. We completely confused. This rebuild should not be this hard. I'm just feeling really discouraged and tired of working on it.

 

[rustystud]

Wildchild I feel your pain ! When a standard rebuild goes south like that it really challenges your resolution. I had a diesel engine that ran great but used coolant. You could pressure test it and it would not leak down. Found out it only leaked when the heads got hot. Had to "Magna-Flux" the heads to find it too. This doesn't sound like your problem since you never lost any coolant right ? Man this is a real stumper ! I'll ask some of my fellow mechanics if they ever came across this before.

 

[Wildchild467]

Wildchild I feel your pain ! When a standard rebuild goes south like that it really challenges your resolution. I had a diesel engine that ran great but used coolant. You could pressure test it and it would not leak down. Found out it only leaked when the heads got hot. Had to "Magna-Flux" the heads to find it too. This doesn't sound like your problem since you never lost any coolant right ? Man this is a real stumper ! I'll ask some of my fellow mechanics if they ever came across this before.

It did seem to use coolant. These are NOS heads that I bought. They should... "should" be perfect. Thank you for asking your friend. I dont know if if could still be a head gasket? We never saw any signs of leakage though... anywhere.

 

[Plane Fast]

Man.. The only way to get sludge like that is to mix oil with something. That something being coolant!


It it could be you have more then one problem. The pistons or ring(blow by) and a out of spec head(coolant)

Dont give up. You are learning a lot about your truck. (As well as us too)

 

[rustystud]

It did seem to use coolant. These are NOS heads that I bought. They should... "should" be perfect. Thank you for asking your friend. I dont know if if could still be a head gasket? We never saw any signs of leakage though... anywhere.

So there is coolant lost then, I didn't know that. Your heads could be cracked then. Even NOS stuff has been known to be faulty. But you get low compression across the board and your leak down test showed "all" cylinders leaking correct ? There is something not aligning up correctly then. Some coolant passage that is coming into contact with the cylinder maybe. Have you overlaid the head gaskets onto the new heads to see if any passage is not aligning up ? Also taking the head gaskets to the block and checking for the same thing ? Also, what is your cylinder liner deck height at ? Is it flush ? I believe there is suppose to be about .002" over height. I need to check the TM's to be sure.

 

[74M35A2]

WC, we have the Magnaflux kit at my work. I will bring it over today. It is a 2 can spray on system, a penetrant, and a developer. Goes on white like covered in flour, and then any cracks show up as a red felt tip like line. Clean off the head, block deck, and piston top surfaces. I think something is cracked. I thought I heard a snap when we were torquing them down. It can't find cracks in passages you can't see, would need a pressure test for that. We pressure tested your cooling system to 7psi cap spec and it held perfectly for over 2 minutes.

 

[skinnyR1]

Pressure tests might need to sit for hours, or overnight, to see the leak down. My truck had a crack somewhere. I had the same sludge and minimal coolant loss. Nearly no coolant in the oil. It would leak down over very long periods of time, days, and also if I did the test when hot after running.
I swapped the motor assuming I had a cracked block.

 

[rustystud]

WC, we have the Magnaflux kit at my work. I will bring it over today. It is a 2 can spray on system, a penetrant, and a developer. Goes on white like covered in flour, and then any cracks show up as a red felt tip like line. Clean off the head, block deck, and piston top surfaces. I think something is cracked. I thought I heard a snap when we were torquing them down. It can't find cracks in passages you can't see, would need a pressure test for that. We pressure tested your cooling system to 7psi cap spec and it held perfectly for over 2 minutes.

If something "cracked" when torqueing down the heads then I would definitely check the liners for proper deck height.

 

[red]

Need to go higher pressure when you test the cooling system. If you go 5 psi over what the radiator cap is designed for the leaks will show up without damaging the system.

 

[rustystud]

Need to go higher pressure when you test the cooling system. If you go 5 psi over what the radiator cap is designed for the leaks will show up without damaging the system.

At work we take the pressure up to 20 psi. If it has a leak it will show by then.

 

[Wildchild467]

At work we take the pressure up to 20 psi. If it has a leak it will show by then.

I agree, higher pressure would be nice. I just worry the radiator/oil cooler may not be made for it. Las thing I wasn't to do is blow the radiator tank up... then I'll be even more cranky. haha.

I have the heads off now. I think I will do what 74M35A2 suggested and do his magnaflux kit. depending on that, the next step might be to have the heads individually pressure checked. I am going to call a place today and see how much it is for that service.

So we know coolant is getting in the oil. I really don't think it would be the engine oil cooler. I mean all of these problems developed right after rebuild and I never, ever touched the oil cooler.


Separate topic: Blowby going past the piston rings?

Here is a picture of a cylinder. I was wondering if I had glazed cylinders or something, but you can still see the cross hatch. I only wiped the cylinders down with a clean rag. The cylinders are smooth and you cant really feel any cross hatch, they just all feel smooth. I would think that is how you would want the cylinders. Looked up pictures of glazed cylinders online, they all indicate the cylinder walls do not have any cross hatch because it all wore off or something. So I am going forward with the assumption that my cylinders are not glazed. Comments welcome.

 

[Wildchild467]

If something "cracked" when torqueing down the heads then I would definitely check the liners for proper deck height.

I was reading something from what Jatonka said a while back about the alignment pins to align the cylinder heads could be sticking up too much and cause issues with interference with the heads. I checked this and all of my alignment pins are fine and do not interfere with the head. I was thinking this could have been the snap sound we heard.

Back to the cracked heads for a moment. Maybe I should look at the pistons a little more. if i was burning coolant in one cylinder, i may have different colored deposits on the piston than the others. maybe one could have some tattle-tale sign I might have a problem with one head and not the other. It would still be good to have them checked. Just food for thought I guess.

Side Note: Thank you all for staying with me on this rebuild. It is helping a lot. The ideas are great and the extra experience is much appreciated. 74M35A2 also has been very supportive and hats off to him for all of his extra time and energy coming over and helping me get this thing closer to done.

 

[74M35A2]

I don't pressure test past radiator cap pressure rating, but each their own with no bad feelings. Maybe OK to do with the radiator out of the circuit, but the top tank of the M35 radiator has a lot of surface area, even 7psi is a lot in my personal opinion. The system will never get above cap pressure, so testing higher is putting the system under a situation it should never really be able to do on its own. I just built a hovercraft for my daughters science class this past weekend with a 120v leaf blower, and it can lift 2 adults easily, with just leaf blower pressure, which is less than 1 psi, but it is applied to 1800 square inches across a 4' diameter plywood disk. I'm not putting more than 7psi on your radiator. But the truck is cold when you are running it, meaning the coolant pressure is near zero with your constant spinning fan, if 7psi doesn't push coolant into the oil, how can 0psi? It is hard for you to see bubbles in the radiator with the curved cap neck, but your head gaskets looked perfect as expected when we pulled the heads. I think something is cracked. If so, now it would just be a matter of finding it, and what to go through to do that? I thought we heard a snap when we were torquing the heads down. I'll drop the Magnaflux kit off at your work or house today on lunch. Read the directions and just follow them. It is simple to use, all aerosol. Best to try it on something cracked first so you know how to use it and know what you are looking for. If nothing surface level shows up, I'd stop throwing time and money after it. You may have to cut your losses on the parts you purchased. Pull the engine from your good running 109, install it, close the hood, and be done with it and onto the next thing. I'll buy the 109 roller and put my DD 6-71T into it with a radiator behind the cab. Scrap the box, and put an old school wrecker boom or rollback bed on the back.You should have done more through diagnostics before pulling it apart. Detailed compression and leak down data for each cylinder, cold and warm. On leaky cylinders, try to trace where the air is escaping to. Could also apply 20psi to long block with radiator removed. You could have an oil cooler leak. I just fixed my washing machine timer, and the float switch air pressure tube plugged with muck 2 days later and overflowed, to be torn back apart again. It happens. Almost anything that can happen, will happen, eventually.

 

[Wildchild467]

Does anybody have experience with the pistons I put in as far as which way the piston rings go on? Since I have the heads off, 74M35A2 suggested maybe I should pull a piston and see which way the rings were put on the piston. When I got the piston kits, I never took the rings off the pistons. The people that put them on was the manufacturer... not me. So it was my assumption that they were put on correctly. Does anybody have a set of these pistons brand new that they can check the rings to see if there are any identifying marks/features on the rings that would tell the orientation if I pulled my pistons out to look?

 

[74M35A2]

Does the manual indicate anything? These are different than what the manual may show though. These may have keystone type rings where they have a taper to them on the inside. You would not know until you pulled one out and looked at the end of one ring closely.

 

[frank8003]

This is for the four ring LDS pistons for some insight.
Now We have to find the like information for your engine.

View attachment LDS rings.pdf
open it as it is three pages

 

[cattlerepairman]

This is for the four ring LDS pistons for some insight.
Now We have to find the like information for your engine.

Yes, I can attest to the fact that the replacement rings come in a pack and two of them are marked "TOP", two are not and it made me very nervous when I put mine on. I also noticed that in the original military pack, oil paper and all, the rings were NOT all in the right orientation as a set. I had to check and flip them accordingly. I hope I got them all right....
If I had swapped complete pistons instead of just the rings, I probably would have done it like the original poster and would not have inspected the rings for correct orientation. Live and learn.