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01-29-2018, 04:13 PM | #1 |
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8RT pulling the heads
I have one cylinder on the drivers side that only has about 30 psi. With oil in the cylinder it bumps up to 100. Something is wrong with the rings or maybe the bore is scored... time to look and see.
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01-29-2018, 04:35 PM | #2 |
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Re: 8RT pulling the heads
What made you check?
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01-29-2018, 08:40 PM | #3 |
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Re: 8RT pulling the heads
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01-30-2018, 08:01 AM | #4 |
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Re: 8RT pulling the heads
Did you squirt some oil in the cylinder and check the compression again. That may help you narrow down if it's a ring issue or not. If the "wet" pressure increases I would "think" rings. But if not it may be a valve not seating properly.
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01-30-2018, 08:02 AM | #5 |
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Re: 8RT pulling the heads
Sorry...forgot what I had just read in your initial post...
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01-30-2018, 10:23 AM | #6 |
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Re: 8RT pulling the heads
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01-30-2018, 10:32 AM | #7 |
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Re: 8RT pulling the heads
Try dumping slowly a quart of auto transmission fluid down the carb at high idle. It is cheaper than marvel Mystery oil. If nothing else all the carbon will be gone . Dont do this in side. Dont ask how I know.
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01-30-2018, 05:43 PM | #8 |
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Re: 8RT pulling the heads
Overall things don't look too bad. Has .080 over pistons, the bores look good, no ridge to speak of just a little carbon. I'd really like to get this truck in "daily driver" shape and be trustworthy so I've decided to pull it and give everything a good looking over. I have a light duty 3-speed to go in it as well and can do it all at the same time. #7 piston has a little chunk missing around the top... that can't be good.
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01-30-2018, 05:50 PM | #9 |
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Re: 8RT pulling the heads
Could it be from a piece of broken ring that then flew out the exhaust?
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01-30-2018, 06:22 PM | #10 |
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Re: 8RT pulling the heads
Is the cylinder with the damaged piston the one with low compression? One would assume so, but you know about ass/u/me.
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01-30-2018, 08:23 PM | #11 |
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Re: 8RT pulling the heads
No, #5 is the low one, #7 (damaged) was 110.
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01-30-2018, 08:45 PM | #12 |
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Re: 8RT pulling the heads
Fifty years ago, I would have buttoned that up and run it. Not these days.
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01-30-2018, 09:50 PM | #13 |
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Re: 8RT pulling the heads
How true tubman, if I needed it to drive to work I'd never even have taken it apart! It actually went down the road pretty good. I think it's just time to take a good look inside, maybe I can breathe a little new life in the old girl.
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01-31-2018, 07:29 AM | #14 |
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Re: 8RT pulling the heads
Looks a little like the 8BA I owned in 1964, when I drained the oil parts of rings came out. One of my Pistons looked worse than yours, I ended up replacing two pistons and a new set of rings, rod and main bearings, no problems after that.
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02-18-2018, 09:40 AM | #15 |
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Re: 8RT pulling the heads
The other head and intake are now off. The RHS cylinder bank look pretty much like the LHS, the bores look good. The valve chamber doesn't look too nasty and I believe there are adjustable lifters in there.
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02-18-2018, 10:18 AM | #16 |
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Re: 8RT pulling the heads
It's not uncommon to find a broken ring on a piston. This can cause a groove to be worn in the cylinder wall due to combustion leakage that happens until the compression gets too low to even fire the cylinder.
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03-02-2018, 10:02 AM | #17 |
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Re: 8RT pulling the heads
A couple more bolts in the transmission then out she comes!
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03-02-2018, 10:47 AM | #18 |
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Re: 8RT pulling the heads
is your truck F1 with a 4 speed? we are going to change out another 4 speed for a syncro 3 speed. we even converted a closed drive 39 1 ton to open drive, a lot of work but well worth the effort for a good driver!!
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03-02-2018, 12:50 PM | #19 |
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Re: 8RT pulling the heads
Mine has the crash-box 4 speed, T-59 I think? That was another reason for me to pull the engine. I have a nice three-speed with new syncros and bearings to go in as well. I suppose those 4-speeds were nice around the farm, but on the street they are awful!
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03-03-2018, 10:22 AM | #20 |
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Re: 8RT pulling the heads
The deed is done!
What will I find in there? All good things, I hope.
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