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| Engine on stand and I need some help. https://slantsix.org/forum/viewtopic.php?t=61026 |
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| Author: | my5thmopar [ Mon Apr 17, 2017 7:08 pm ] |
| Post subject: | Engine on stand and I need some help. |
Background: This 73 slant was thought to have only 36K miles on it. It came from a one owner elderly man whose grandson pulled the /6 for a SB install. The pedals and car general condition led me to believe it was low miles. The first thing I did was a cold engine compression test with plugs out, throttle open and cylinders dry. I should have done it warm but, didn't think to. It hit 90-100psi first stroke and 150psi after 5 or 6. thread here: http://www.slantsix.org/forum/viewtopic.php?t=60032 I started the engine on a makeshift run stand and no smoke, no noise. That's why I decided not to rebuild it. I am resealing the engine and when I took the valve cover/oil pan off, it was incredibly clean. The engine was washed with solvent inside and out then sprayed with clean 5w-30. I was replacing the valve stem seals. Problem: I removed all spark plugs. I removed the rocker shaft and put 100 psi in #1 to hold the valves. I did not have piston at TDC but, read on. The #1 had what seems to be a lot of blow by. The #2 had air below piston. Cylinder 3-6 more past valves. Is my method incorrect or did washing the oil off cause this or do I have an issue? If I was doing a leak down test, I would conclude there are issues. I really didn't want to get into pulling the head, rebuilding, machine work. Anything thoughts before I go down that road? |
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| Author: | Joshie225 [ Mon Apr 17, 2017 9:00 pm ] |
| Post subject: | |
I would put it in the car and run it. It's not uncommon to have a little carbon or rust on a valve seat or sticky rings on an engine that's been sitting. Run it a while and see if she gets better or worse. If you have to pull the head for a valve job it can be done from the engine compartment. |
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| Author: | Pierre [ Mon Apr 17, 2017 9:25 pm ] |
| Post subject: | |
Get a piece of soft metal such as aluminum and put it on a stem, then tap it with a small 3lb sledge. Or perhaps use a brass hammer. Just get the valve to move a little against spring pressure so it snaps back shut. Do this while you have air in the respective cylinder, and see if it's tone changes afterwords. Guide issues are a possibility. If you can't get the valves to seal after a couple rounds of this... I suppose you can run it again on your stand and let it warm up, then re-check. If all is well, great. If not, your due for a valve job. At least this way you can narrow it down to the specific valves so you can closer investigate the seat and any wobble in the guide upon disassembly. On second thought do it without air then re-pressurize. Less force required to get the valve to move. |
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| Author: | my5thmopar [ Thu Apr 20, 2017 9:13 am ] |
| Post subject: | |
The new seals are in and taping the valves didn't seem to make a difference. I'm going to move forward with a new timing chain and a reseal. A buddy gave me 3-4 gasket kits and several slant parts. I'm not going to be out any money, just time and energy doing the swap. I also, have a peanut head and a 60 over 1968 BH block that may get a proper rebuild. My 1964 D100 slant is tired and rattles at startup so, that's why I'm doing all this. Thanks Craig I couldn't find that thread about a common oil leak at the back of the block? |
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| Author: | Joshie225 [ Thu Apr 20, 2017 11:29 am ] |
| Post subject: | |
If you have free gaskets I would pull the head and disassemble it for inspection. Lapping compound is cheap in case the valves and seats could use a touch-up. |
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| Author: | coconuteater64 [ Thu Apr 20, 2017 11:35 am ] |
| Post subject: | |
Quote: If you have free gaskets I would pull the head and disassemble it for inspection. Lapping compound is cheap in case the valves and seats could use a touch-up.
This
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| Author: | Pierre [ Thu Apr 20, 2017 9:23 pm ] |
| Post subject: | |
I'm thinking things are beyond lapping if it really is a lot of blow by like he says. |
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| Author: | SpaceFrank [ Fri Apr 21, 2017 10:41 am ] |
| Post subject: | |
Another vote for pulling the head now while you've got the engine on the stand. If all it needs is a good lapping, you can knock that out easy. New stock valves are cheap on RockAuto if necessary. If the head needs machine work, well... better to know that now. |
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| Author: | my5thmopar [ Fri Apr 21, 2017 2:40 pm ] |
| Post subject: | |
If I pull the head, I guess I could have the peanut head machined and milled then use it. I'm going to lose compression with a fiber gasket verses the steel on there now, correct? |
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| Author: | DusterIdiot [ Fri Apr 21, 2017 5:30 pm ] |
| Post subject: | Yep..but... |
Quote: I'm going to lose compression with a fiber gasket verses the steel on there now, correct?
Yes, but you can mill another .020 off the head and make up for it...
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| Author: | Rick Covalt [ Sat Apr 22, 2017 4:58 am ] |
| Post subject: | |
Quote: It hit 90-100psi first stroke and 150psi after 5 or 6.
How can it have a lot of blow by or a valve leaking and still have 150 PSI. That dosen't make sense to me? 150PSI sounds like a healthy engine number.
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| Author: | Dart270 [ Sun Apr 23, 2017 12:55 am ] |
| Post subject: | |
I would also just put it in the car and run it. Those comp numbers sound fine to me, especially for a dead cold engine. Did you adjust the valve lash before the tests? Lou |
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| Author: | Tim Keith [ Mon Apr 24, 2017 6:32 pm ] |
| Post subject: | |
You might soak the pistons/rings with your favorite top end cleaner. With low miles the motor may have been used for short trips. The rings might have carbon buildup. This motor doesn't sound too bad to me. Tim |
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