1965 Excessive Oil Consumption

Olympus 200

Olympus 200

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Thunderbird Year
1965
Hi all
I've just installed a reconditioned 390 in my '65 and everything seemed to be going OK as I broke the engine in on local trips. However after about 200 miles the oil consumption suddenly became excessive ie a pint in 50 miles. I took the mileage to 300 to make sure I wasn't misreading the dipstick before investigating further. I've removed the plugs and #5 cylinder is wet with oil inside, the plug is also a lot darker than the others. This is a weird one. I find it hard to believe the rings or valve guides are at fault as it is virtually a new engine. I also have my suspicions about #6 and #8 but they are nowhere near a bad as #5. The right cylinder bank is OK.
All thoughts gratefully accepted.
 

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Olympus 200 said:
Hi all
I've just installed a reconditioned 390 in my '65 and everything seemed to be going OK as I broke the engine in on local trips. However after about 200 miles the oil consumption suddenly became excessive ie a pint in 50 miles. I took the mileage to 300 to make sure I wasn't misreading the dipstick before investigating further. I've removed the plugs and #5 cylinder is wet with oil inside, the plug is also a lot darker than the others. This is a weird one. I find it hard to believe the rings or valve guides are at fault as it is virtually a new engine. I also have my suspicions about #6 and #8 but they are nowhere near a bad as #5. The right cylinder bank is OK.
All thoughts gratefully accepted.
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I would talk to the guy or gal that "reconditioned" your engine, good luck
 
Were you careful to properly file/gap the rings when you put them on the pistons? If rings are not gapped correctly, they will expand with heat and crack/break.
 
Pull the valve covers, occasionally valve stem seals can ride up and cause this issue. Just push them back down.
 
Make sure the oil isn't leaking out the bottom of the engine. Do a compression check and see if there is a low cylinder or two. 74Harley is spot on about misplaced valve stem seals. If ring gaps are incorrect sure that can cause oil consumption. Have someone follow you while you're getting on the engine and see if it's burning oil.
 
64ZCODE said:
Make sure the oil isn't leaking out the bottom of the engine. Do a compression check and see if there is a low cylinder or two. 74Harley is spot on about misplaced valve stem seals. If ring gaps are incorrect sure that can cause oil consumption. Have someone follow you while you're getting on the engine and see if it's burning oil.
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Dry as a bone under the engine. Compression check on all cylinders using my cheap 70s gauge a nominal 180psi on all 8. All ring gaps OK on installation. What mystifies me is that the oil consumption suddenly got very bad. I'll have a loom at the seals, hope its that simple!
 
74 Harley said:
Pull the valve covers, occasionally valve stem seals can ride up and cause this issue. Just push them back down.
Click to expand...
I'll have a look. Hope its that simple as at the moment I'm thinking a lot of doom and gloom . . .
 
Dude, consistent compression across all 8 is a great sign. You may just be going through a break period.
 
Would show up as an intake vacuum leak? My '64 has 17 inches of mercury vacuum at idle when carb mix is adjusted.
 
64ZCODE said:
Dude, consistent compression across all 8 is a great sign. You may just be going through a break period.
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That's what I want to hear! I'll hang onto that thought while I put more miles on the car whilst watching the oil like a hawk. Funny the problem should arise so suddenly.
 
Many thanks to those that offered assistance via this thread, I've learned a lot.

Finally resolved the problem . . .

Replaced the inlet gaskets and used silicone on the china walls. Noticed oil in the inlet tracts and on the valves but couldn't be sure whether it leaked in during the time between loosening the manifold and actually lifting it off, or whether it got there via the valve stems, or both. The new gaskets didn't resolve the problem. Discussed the matter with a local classic car mechanic and we installed new viton positive valve stem seals which replaced the umbrella type supplied with the Felpro kit. Problem solved, negligible oil consumption!!

Still wondering what caused the sudden increase in oil consumption after about 300 miles. I'm wondering whether the engine got a bit hot after 25 minutes in a traffic queue and the seals got less pliable and stopped sealing as well.

Another factor may be the aftermarket rocker assembly which may be allowing more oil to escape over the valve springs and overwhelming the umbrella seals once they had become less pliable.

Immensely relieved as was beginning to doubt my engine rebuilding abilities!

By the way, does anyone know what type of valve stem seal Ford used originally?
 
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