Piston Rings Worn Out, Time for a Rebuild

[Wildchild467]

Good question. It's too late for me to look at the ones in my truck now, but I still have my old ones to measure. I'll get that data tomorrow. I believe the oil pressure regulator will prioritize oil going to the bearings first. After oil pressure is met, the access oil goes to the oil nozzles to cool the pistons. There are two pressure relief valves in the oil pressure regulator. One for the bearings and one for the nozzles I believe.

 

[Wildchild467]

...Read this post... G.

These are the same pistons that I used, even the same date code.

Another things to add since you said you were comparing pistons, I have a comparison of the LDT pistons I took out to the new LDS pistons I put in...

 

[tommys2patrick]

I was wondering if a change in mass helps them develop a little more horse power than the LDT versions? The rings look like they are arranged a bit differently as well. Very good to follow your work.

 

[Wildchild467]

I was wondering if a change in mass helps them develop a little more horse power than the LDT versions? The rings look like they are arranged a bit differently as well. Very good to follow your work.

Im not exactly sure on the change in mass developing more power. They sure are not light weight piston pins since they are solid and not hollow.

 

[gringeltaube]

I just weighed those two to compare and can confirm now that there is no change in mass really: LDT piston #11668483, 4 rings & solid pin = 3196 g
LDS piston #12380090, 3 rings & solid pin = 3206 g. The difference of only 10 g (= 0.3%) could well be within production tolerances, IMO.

I also confirmed that the oiler nozzles all have the same diameter: 1.55mm. Which means to me that the double-squirters will put twice as much oil near- or into the piston groove - and of course add in cooling, if.... (only if!) the pump still has enough flow capacity, once the oil reached normal operating temperature.



G.

 

[Wildchild467]

I just weighed those two to compare and can confirm now that there is no change in mass really: LDT piston #11668483, 4 rings & solid pin = 3196 g
LDS piston #12380090, 3 rings & solid pin = 3206 g. The difference of only 10 g (= 0.3%) could well be within production tolerances, IMO.

I also confirmed that the oiler nozzles all have the same diameter: 1.55mm. Which means to me that the double-squirters will put twice as much oil near- or into the piston groove - and of course add in cooling, if.... (only if!) the pump still has enough flow capacity, once the oil reached normal operating temperature.



G.

I agree. Higher volume would be nicer to have for these oil nozzles but i don't know how much of a disadvantage it would be in the big picture not having the LDS 465-2 oil pump. More is better but who knows how much. Another thing to consider, the oil cooler for that LDS 465-2 engine was different as well. I am not sure changing just the pump would work because what happens if it also needs a different oil cooler as well? Just thoughts.

I'm fairly certain that once the oil pressure relief valve opens for the bearings, that access oil gets diverted to the piston oil nozzles instead of just dumping it in the oil pan. It would be like two pressure relief valves hooked up in series. Can you confirm? I would still think two is better than one with these nozzles though. I need to get the mechanical gauge on there soon so I can take data to make sure my electric oil pressure gauge is reading correctly.

 

[74M35A2]

By moving to twin oil squirt tubes for piston cooling, with no oil pump capacity upgrade, you are likely not spraying said oil as far up under the skirt of the piston as intended. Maybe no big, but just sayin'.

 

[gringeltaube]

Life isn't fair: more we learn, more Qs. we have...
Seems like "trial-and-error" - combined with collective experience may take us furthest, in this case...?


Anyone else here, running these twin-nozzles in their Multi's please report back results!




G.

 

[gimpyrobb]

Do you guys think you might be over analyzing this? I understand that there are 2 different pump volumes here, but 22 or 29 gallons per min is a LOT of volume.

 

[gringeltaube]

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).

I really want to know two things:
1) Why did the engineers decide that our common oil pump wasn't enough for the LDS465-2 motor?
2) Who else has installed these twin-nozzles and already driven several K-miles, after that?



G.

 

[rustystud]

Since our initial oil pressure is around 100 PSI and is then reduced down to around 60PSI at cruise that there would be no problem using the LDT oil pump. Also the oil galley is .750" diameter (3/4") before it goes to the regulator. So again I don't believe there would be any problem with volume either.

 

[Wildchild467]

By moving to twin oil squirt tubes for piston cooling, with no oil pump capacity upgrade, you are likely not spraying said oil as far up under the skirt of the piston as intended. Maybe no big, but just sayin'.

Agreed, we don't know.

 

[Wildchild467]

Do you guys think you might be over analyzing this? I understand that there are 2 different pump volumes here, but 22 or 29 gallons per min is a LOT of volume.

Maybe but thats what we do Gimp! haha! Engineers have to over think everything. To me, thats half the fun of the hobby. I love knowing how things work. Then the more I know, the more I can help others in the hobby. You and other guys helped me a lot on here and I just try to pass it on

 

[74M35A2]

I'm not helping you clean up the oil slick on your garage floor. It looks like the Exon Valdez pulled in and rolled over on its side in there. At least your garage floor will never rust...

 

[Wildchild467]

I'm not helping you clean up the oil slick on your garage floor. It looks like the Exon Valdez pulled in and rolled over on its side in there. At least your garage floor will never rust...

I know. My garage is a total pit right now. It will be a couple day job cleaning that up. Pressure wash my old heads and use them for weight in the back of the jeep for the winter time!

 

[Rattlehead]

I would love to hook a load on it to see how it runs but I don't have a trailer or anything that is easy to hook on to. So far so good though!

Tom, you almost had an opportunity last weekend to load it down real good, with about 23k lbs (M45 + M105) towbarring my sorry azz off of Woodward! Thanks again for hanging out all that time to make sure I could get the part to get my deuce back running again. Long story short, I had a fuel line pull out of the injection pump and just needed a 3/8 ferrule to put it back together. I could have sworn that I put extras in the truck, but umm, no. Chevrolet Certified Service crew made a run a couple of miles (an hour+ due to traffic) down the street and picked one up for me. Tom came by right after they left and waited with me in case we couldn't fix it and I would need a tow.

 

[Wildchild467]

Tom, you almost had an opportunity last weekend to load it down real good, with about 23k lbs (M45 + M105) towbarring my sorry azz off of Woodward! Thanks again for hanging out all that time to make sure I could get the part to get my deuce back running again. Long story short, I had a fuel line pull out of the injection pump and just needed a 3/8 ferrule to put it back together. I could have sworn that I put extras in the truck, but umm, no. Chevrolet Certified Service crew made a run a couple of miles (an hour+ due to traffic) down the street and picked one up for me. Tom came by right after they left and waited with me in case we couldn't fix it and I would need a tow.

Glad I could help!! Anytime!

 

[Wildchild467]

Well, its been about 3 months since I got the rebuild done and I'm not completely satisfied. New pistons,rings, sleeves, NOS heads, New style head gaskets and I still have blow-by coming out of my slobber tube. I also have some thick grease looking stuff on the bottom of my oil fill cap and inside the valve cover. I also seem to be losing coolant somehow and I don't know where it is going. My oil is not milky or increasing the level, so I'm not sure. I have the pump turned up pretty good and can get over 15PSI of boost, so I don't know if its a blown head gasket or what. I did a leakdown test last night and the numbers seem to be all over the place and I don't really trust that data because when i roll the engine over a little with the leak down test in progress, I can change the numbers a little bit after I stop turning the crank slightly (its hard to explain). I also did a compression check since I was right there and I got all around 340 PSI on 4 of the 6 cylinders. I didn't get a chance to check the other 2 because my copper sealing washer got stuck in one of the holes and i couldn't get it out. I was frustrated working in low light and not being able to get the sealing washer out, I needed to call it a night. I throw all this money at it in new parts because I wanted the best running Deuce and not have to work on it for a long time... and it still is not 100%. I would ask for advise but I'm really dont know what else it could be.

EGT's are a higher than they were at first as well. I can run hot just empty and it never used to be like that right after the rebuild. So that is an indication something is not right. I can get up to 1150 pulling away from a light if I take off as fast as I can. I never adjusted the fuel rate at any time before or after the rebuild, so not sure what is going on. I am not thinking that is the cause of the problem.

The only possible theory I can think of is that one of my head gaskets is leaking. When I put the head gaskets on, I used the copper spray gasket on the new gaskets. The stuff is made by Permatex. I'm sure you guys have experience using it. When I did gaskets before, I did not use the copper spray gasket stuff and put them on dry. That is the only difference. I'm at a loss on where to go. Next step I guess is bring it in the garage and loosen all of the valves and do another leakdown test where I know all of the valves are shut and see if I get any different numbers. Maybe pressurize the cooling system with 7 PSI while I am at it. I only started loosing coolant after the rebuild, so I doubt it is my oil cooler because I never touched that.

Opinions welcome I guess. I'm just so mad at the thing I almost could care less about fixing it.

 

[cattlerepairman]

I only started loosing coolant after the rebuild, so I doubt it is my oil cooler because I never touched that.

Opinions welcome I guess. I'm just so mad at the thing I almost could care less about fixing it.

Man, that aint happy days. As for blow-by, it has been reported that, even after a good and thorough rebuild, these engines will still have blow-by. Some more, some less.

I fully agree with the line of testing that you began. Compression and leakdown for starters. I am not sure that moving the crank is a good idea during a leakdown test. First, you will move the piston, thereby altering the pressure inside the cylinder. Secondly, if a valve is "just" closed, the touch of the rocker arm might be enough to make it leak. Cylinder should stay TDC and no movement. Others will chime in.

I would not tear apart what you already rebuilt, unless the facts do not leave any other choice. Look at the things you did not touch. Murphy is an *sshole that way.
Which coolant do you run? The orange/red truck stuff? That should be pretty decent for leaving crusty trails if you lose it externally (any hose connection or even the water heater core). You may only lose coolant when it is hot and fully pressurized (i.e. driving).

The oil/water cooler should be looked at. It can trap incredible amounts of crud and actually contribute to overheating. You need the two O-rings and the two gaskets (heat exchanger to cooler base and heat exchanger to lid). It is not hard to do and I bet the heat exhanger needs a good wash anyway.

Did you flush the block and the rad before you filled everything? I noticed that, aside from the crud that is in there anyway, the drying out of the water jackets during the rebuild seemed to "produce" more crud and stuff flaking off.

Also, the fuel setting on the IP might have been a good match pre-rebuild, but it might need to be tweaked for the rebuilt engine.

 

[74M35A2]

6-71t