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| oil consumption https://www.slantsix.org/forum/viewtopic.php?t=50583 |
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| Author: | mopardean [ Sun Dec 16, 2012 7:22 pm ] |
| Post subject: | oil consumption |
a while back i had a local machine shop rebuild a slant i had from a 1975 low mileage duster. it was left over from another project and after it was rebuilt i installed it in my 87 half ton. Since then i have had lots of problems mainly excessive oil consumption. this weekend i got frustrated to the point of doing a full compression and leak down test. Results as follows: Compression Leakdown % 1 119 20 2 120 12 3 120 20 4 120 n/a 5 125 6 6 114 22 The motor starts and runs fine. it is a little lumpy idling after having installed a comp cam 264 (would not do that again). The plugs look great, no smoke but its using a qt of oil every 500 miles. It does leak under the head from the push rod slots (i have tried to fix this 3 times) but nothing that could account for all that missing oil. I pulled the valve cover and things look nice and clean, pcv valve working great and ditto the valve cover oil breather hooked to the carb The motor has about 8K miles since rebuild and i did notice some air whistling out the dip stick during the leakdown test. That i believe indicates rings. I ran 30W not detergent for the first 2000 miles or so after rebuild. Since then Valvoline 10-30. is it possible the rings havent seated yet after all these miles? is there any additive or special oil i could try to seat the rings? The leakdown test could be better but could that account for all the missing oil without smoke or fouled plugs? Incidentally the motor was bored 20 over at time of rebuild. Any help would be GREATLY appreciated as i am getting mad enough to pull the engine and start all over...this time maybe redo the hydro motor that came from the truck originally |
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| Author: | bigslant6fan [ Sun Dec 16, 2012 9:48 pm ] |
| Post subject: | . |
What kind of valve seals did you use? Those perfect circle teflon seals are known to pop off the guide bosses and guzzle oil. |
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| Author: | mopardean [ Mon Dec 17, 2012 7:31 am ] |
| Post subject: | |
i try to find out which seals were used... but during the leakdown test i could detect no leakage at the valves, thru the carb or exhaust |
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| Author: | robertob [ Mon Dec 17, 2012 9:08 am ] |
| Post subject: | |
You would not see pressure leakage through the valve stems/seals - the valves are closed when you do the test. |
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| Author: | mopardean [ Mon Dec 17, 2012 9:14 am ] |
| Post subject: | |
excellent point how can i check for this? pull the head and inspect? its a real mystery because it just doesnt smoke and the plugs looked close to perfect.... |
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| Author: | robertob [ Mon Dec 17, 2012 9:48 am ] |
| Post subject: | |
You might be able to see them through the valvesprings with a flashlight. Just pull the valve cover and see what you see. |
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| Author: | mattelderca [ Mon Dec 17, 2012 10:34 am ] |
| Post subject: | |
I am not really a /6 expert but I'll throw my two cents in. Do a wet compression test and see if the numbers come up. What type of final hone was done? was the final hone done to the ring manufacturers specs? I'd say the rings may not have seated well. I hear debates about proper start up to seat rings all the time, but IMHO if they don't seat by the second warm up, they never will. Of course in the slanted land that you guys live in I could be way off. |
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| Author: | SpaceFrank [ Mon Dec 17, 2012 11:43 am ] |
| Post subject: | |
Quote:
its a real mystery because it just doesnt smoke and the plugs looked close to perfect....
If it's not smoking and the plugs look clean, how do you know you're burning oil?You mentioned a leak at the "push rod slots." I'm not sure what you mean by this; can you clarify? Is oil coming out at the head gasket, valve cover gasket, or spark plug tubes? |
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| Author: | DusterIdiot [ Mon Dec 17, 2012 6:05 pm ] |
| Post subject: | These two... |
Quote: Is oil coming out at the head gasket, valve cover gasket, or spark plug tubes?
1975+ engine, no plug tubes if using 1975 head or his 1987 head.These notoriously leak at the head gasket between the block and head at the lifter gallery. Easiest prevention is after installing the head and torquing the head to run a little RTV into that gap using your finger to smear it into place (Doc Dodge Slant Building Tip #76). -D.Idiot |
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| Author: | '67 Dart 270 [ Mon Dec 17, 2012 7:58 pm ] |
| Post subject: | oil consumption |
Hi, My slant is a new rebuild, same issue, losing about a quart of oil every 500 miles. Doesn't smoke, runs great, where's the oil going? I did find that the valve cover is leaking on the back passenger side corner. Went underneath, the tranny pan is covered with oil and I found oil on the exhaust (passenger side) pipe mid-way back... Do 225 vavle cover's typically leak back there? I had the tin cover, it was doing the same thing. switched to Offy cast cover, same thing! thanks, '67 Dart 270 |
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| Author: | '67 Dart 270 [ Mon Dec 17, 2012 7:59 pm ] |
| Post subject: | oil consumption |
BTW, it doesn't appear to be the rear seal....although I find some oil on the cover over the bottom of the tranny, the oil pan area near the rear seal is dry.... |
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| Author: | mopardean [ Mon Dec 17, 2012 8:31 pm ] |
| Post subject: | |
i was thinking it must be the rings since the leakdown was marginal on some cylinders plus i heard air whistling out the dip stick tube when the cylinders were pressurized. Dusteridiot is correct it is leaking on the distributor side of the block around the head gasket lifter trays. i will pull the head again and try to seal it again but i dont think its leaking enough to account for all that oil consumption. Incidentally the block and head all are from a 75 Duster I dont know what kind of final honing they did on the cylinders. i hate to think of pulling the engine and tearing it all down again but i might have to do just that. any and all ideas appreciated. |
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| Author: | mopardean [ Mon Dec 17, 2012 8:34 pm ] |
| Post subject: | |
of course i meant lifter gallery not lifter trays. its late and i am an idiot.... |
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| Author: | DusterIdiot [ Mon Dec 17, 2012 9:56 pm ] |
| Post subject: | Hey!!! |
Quote: its late and i am an idiot....
Don't take my title...I like being the board village A-body Fastback Idiot!!!! You might be able to shortcut and not run the engine all weekend and maybe mop up the oil on the engine and run a RTV bead in that spot and leave it to skin over a day or two...before pulling the head and doing the full monty. Quote: Do 225 vavle cover's typically leak back there?
Not all but some do, I got a couple that way...-D.Idiot |
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| Author: | mopardean [ Tue Dec 18, 2012 9:49 am ] |
| Post subject: | |
cant there be 2 idiots on here?? LOL |
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