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Piston lube??

2K views 20 replies 15 participants last post by  machine shop tom 
#1 ·
Hey just wondering what fluid you guys use to coat your pistons and cylinders in when installing the pistons. Will some 10w30 work, or is there a different grade or assembly lube that I should use for this??

Thanks,
Keith
 
#5 ·
Don't mean to sound disrespectful, but youve got to be joking....WD-40? That stuff is cra^, after the carrier solvent leaves what is left behind is a yellow goo. Why would you not use the oil that is designed to run in the engine? WD-40 has minimal lubricating capabilities compared to engine oil.

Vince
 
#6 ·
Lube

No disrespect taken.....

Actually almost all the ring manufacturers recommend WD-40 for installation..

I can only speak for me but the last 40 or 50 engines that i have built i used WD-40 on the rings/piston during installation with zero issues. Even though i don't have a bunch of data from when i used to use oil, i do know that since i switched my initial leak-downs are a bit better. They went from an average of 8 to 10% to 6 to 8% on the test stand.


Keith
 
#9 ·
k-star said:
No disrespect taken.....

Actually almost all the ring manufacturers recommend WD-40 for installation..

I can only speak for me but the last 40 or 50 engines that i have built i used WD-40 on the rings/piston during installation with zero issues. Even though i don't have a bunch of data from when i used to use oil, i do know that since i switched my initial leak-downs are a bit better. They went from an average of 8 to 10% to 6 to 8% on the test stand.


Keith
sure your leakdown would improve initialy because you ae getting rapid wear frome no lubication. i have toured catterpillars engine plants they use lube oil as initial piston and ring lubrication, but of coars they hope for very long engine life. cliff
 
#10 ·
cliff tate said:
sure your leakdown would improve initialy because you ae getting rapid wear frome no lubication. i have toured catterpillars engine plants they use lube oil as initial piston and ring lubrication, but of coars they hope for very long engine life. cliff
I don't believe thats an issue because after the engine is running for 2 or 3 seconds the cylinder walls have all the normal oil splash, same as if the car sat over night in your garage.

A few of those engines have 50,000 plus and at least 1 has 100,000..with no excess leak down issues.

Rings in a diesel engine live in a different world then in a gas engine...

Keith
 
#11 ·
engine pre lube...

:p :p :p Hi,i have probably built about 30 engines over the years. mostly sbc,with a few sbf threw in. i have ONLY ever used STP,on pistons,cylinders,cam,lifters,and bearings. and timing components. ive never had a problem i use a distributer (cut down) for pre start lubing, after starting and running (while watching the temp guage) i pull the plugs and clean them,after about 20 minutes of run time at 2000 rpm,i change oil,and filter,then cut filter to inspect. :D :D :D
 
#12 ·
I also use WD40 exclusively, I have done over 100 engines since I began using it over 20 years ago from snowmobiles/14.000 rpm drag bikes and many FE Ford engines. Never had a failure and some have 40,000 miles and more. I don't believe the analogy with Cat is appropriate, they are diesels and have larger pistons as well as ring pressures and everthing else..their longevity has nothing to do with break in lubes, it's all in component design. The reasoning, and I think if you check with some pretty big name engine builders they do the same, is that oil will get behind the rings and can "coke" up over time and the WD40 allows virtually immediate sealing of the rings...and as was pointed out, by that time the lube system is working, especially when primed as should be.
 
#13 ·
woodz428 said:
I also use WD40 exclusively, I have done over 100 engines since I began using it over 20 years ago from snowmobiles/14.000 rpm drag bikes and many FE Ford engines. Never had a failure and some have 40,000 miles and more. I don't believe the analogy with Cat is appropriate, they are diesels and have larger pistons as well as ring pressures and everthing else..their longevity has nothing to do with break in lubes, it's all in component design. The reasoning, and I think if you check with some pretty big name engine builders they do the same, is that oil will get behind the rings and can "coke" up over time and the WD40 allows virtually immediate sealing of the rings...and as was pointed out, by that time the lube system is working, especially when primed as should be.
i do not agree with the statement diesel engine rings and conditions are so different i have rebuilt many of both and the rings are the same ,all are ether chrome most molley top, the only difference is the oil ring which heavey duty gas engines ,garter spring behind the oil ring. but we all have our ways and beleifs, i pre lube all my gas engines and lube all components with engine oil, have yet to have a failure(touch wood)
 
#15 ·
It makes good sense to me to use WD40 after pointing out some of the unknowns in there. I dunno how long it would take really for the oil to coke in the ring land, but being the top ring is almost instantly hot it wouldn`t take long, and anytime coked oil is in the ring land it will never seal up properly and cause accelerated wear. Many high mileage engines I`ve disassembled over the years all had this issue, after a while there is no way to stop it. Problem is it gets so hot in the ring lands the coked oil becomes very hard, without a good cleaner it`s very difficult to get out, for the cheap when reusing the stock pistons we would spray the ring lands with gasket remover. worked like a champ every time.
 
#16 ·
I like to dip the entire thing in a coffee can filled with plain engine oil. Don't use anything with additional molybdenum like can be found in many oil additives like STP. Moly is a great filming agent but it makes a horrific and incredibly hard ash. The oil left in the chambers will burn when you fire it up and you don't want anything but oil in there. That means I personally avoid break in lube, STP, gear oil, or greases. Just stick with the oil you'll be filling it with later and you'll be fine.

I've heard that WD40 works well, but (regardless of its other properties) its too thin for me. It lacks the viscosity to properly lube something like rings so I don't use it.

But this is all just opinion based on research I've done for my own engines over the past several years, I don't have all the answers. I do know that I've only ever had one issue with rings in any of my builds and it was the time I decided to use 90w gear oil on the pistons. I figured the extra moly and viscosity would help it stay in place until I fired it. What I got was way too much oil staying there and the result ended up being rings that coked up with a VERY hard ash. They stuck, the bores scored, and I was back at square one. Every engine I've built using engine oil on the pistons has never had a ring issue, some of which have well over 100k on them now.
 
#19 ·
k-star said:
WD-40


Keith
I've used Liquid Wrench for the rings (same thing) on many stock gas engine rebuilds. For performance builds or diesels I still use engine oil for the rings and cylinders. For most everything else in an engine I use Lubriplate #105. Once again even for stock cam break-in, it's always worked fine. For performance flat tappets, I definitely use cam lube.
 
#21 ·
One could probably use salad oil (DON"T) if the bores are finished correctly. I don't think the oil coking thing is a valid issue. If it were, the OEMs wouldn't be using oil for their assemblies. As long a SOMETHING is present to lubricate the rings until the engine oil gets to them it's ok.

If you are having good results from whatever you are using, I see no reason to change.

tom
 
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