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Topic Review (Newest First)
07-31-2010 04:40 AM
80 mich bu
Quote:
Originally Posted by 27 t
this is how i would ck for an internal vacuum leak back in my jeep days this was a very common problem on the 318 = 360.. remove and plug pcv remove and plug breather.. take a vacuum gage with the large adp install into pcv grommet in the valve cover.. start the eng bring up the idle a little and see if the gage pulls a vacuum.. if you have a vacuum than more than likely you intake gasket is leaking... anyone disagree would it work on a sbc....
Thanks for the tip... Car going back next week, hopefully they will find it.
Thanks again for the reply....
07-30-2010 12:31 PM
27 t this is how i would ck for an internal vacuum leak back in my jeep days this was a very common problem on the 318 = 360.. remove and plug pcv remove and plug breather.. take a vacuum gage with the large adp install into pcv grommet in the valve cover.. start the eng bring up the idle a little and see if the gage pulls a vacuum.. if you have a vacuum than more than likely you intake gasket is leaking... anyone disagree would it work on a sbc....
07-30-2010 10:06 AM
80 mich bu
Quote:
Originally Posted by 406 bug
What are your vacuum readings???
I don't know, had a local well known engine shop do my headwork..its going back in monday and the are going to check the intake manifold gaskets. Vacuum appears to be good, I'm still running power steering & brakes, lock up converter with no issues. All I know is I'm going thru a quart of oil every 300 miles. I talked to an Edelbrock tech, the shop that did the shortblock and the shop that does my dyno tuning and they are saying intake leak.
07-29-2010 09:56 AM
406 bug What are your vacuum readings???
07-29-2010 06:45 AM
80 mich bu
Quote:
Originally Posted by y2k600f4
Thanks for this info....exactly what I was looking for. Wonder if this is/was or part of my problem all along ? Cork gaskets are not being used, but wondering if there is some issue with the fitting of the intake and it needs machining ? I guess I'll wait and see what the builder thinks; hopefully this can be diagnosed as either being and issue or not.
Hi...was wondering what your outcome was...I'm going thru the same problem
08-13-2009 10:05 AM
y2k600f4
Quote:
The times I've had sealing issues and oil usage like this, you couldn't see oil evident on the backs of the valves, you could only feel it on the port walls using a dry finger. Fuel wash is constantly cleaning them and they are hotter while the engine is running than the port, the oil comes off them easier(thinner).
Thanks for this info....exactly what I was looking for. Wonder if this is/was or part of my problem all along ? Cork gaskets are not being used, but wondering if there is some issue with the fitting of the intake and it needs machining ? I guess I'll wait and see what the builder thinks; hopefully this can be diagnosed as either being and issue or not.
08-13-2009 09:33 AM
ericnova72 You may find that the cork end seals do not allow the intake to pull as tightly down to the head as they need to be. I never use them anymore for this reason, it has tripped me up a couple of times, the hot tip is the trick of using a 3/16" or so bead of RTV instead of the cork strips. Lay a nice bead and let it skin over before laying the intake on.

The times I've had sealing issues and oil usage like this, you couldn't see oil evident on the backs of the valves, you could only feel it on the port walls using a dry finger. Fuel wash is constantly cleaning them and they are hotter while the engine is running than the port, the oil comes off them easier(thinner).

I don't know if your mechanic's pressure test idea will work but it should, it's just like a leakdown test in the cylinders basically. Wouldn't hurt to try, fabbing up a plate and fitting to cover the carb opening should be easy.
08-13-2009 09:18 AM
y2k600f4
Quote:
Originally Posted by ericnova72
If this is with an aluminum intake, what gasket brand and type have you been using?? What sealants?? What brand intake?? Heads or block milled?? What end seals used on the block-to-intake area??

Aluminum intake: Professional Products Crosswind (air gap clone), felpro 1206 gasket with RTV sealant on end seals. Heads and blocks not milled.

First rebuild it had a felpro 1205 sealed in the same manner. I then pulled the intake at around 700 miles or so (suspect sucking oil from galley) but I did not see any evidence in the intake ports of oil laying on backside of valves; replaced with 1205 in same manner. Recent rebuild builder used a 1206 (better port match) and sealed up in the same standard manner. He wants to rule out intake, but I don't understand if the back of the intakes were clean in the past and assume they still are now that intake sealing could even be a possible issue.
08-13-2009 09:11 AM
ericnova72 If this is with an aluminum intake, what gasket brand and type have you been using?? What sealants?? What brand intake?? Heads or block milled?? What end seals used on the block-to-intake area??
08-13-2009 08:32 AM
mitchc Can you provide some more engine info. What heads, intake, valve covers. Have you had the heads off? If so what did the pistons look like. If you have a clean out side edge on the pistons that would indicate oil coming from the rings. What does the exhaust ports look like. dry or wet with oil.

I just went thru this with a friends 32 he built a 350 and had a oil problem on the right side and we could not find it. new rings, new .003 over valves in the heads new viton seals, etc. nothing helped. we noticed that #8 exhaust port was wet with oil so we check the exhaust valve and it was good. We put a diffrent set of heads on and the problem went away. I think there was a crack in the head down around the short inside bolt and it was getting into the exhaust.



Quote:
Originally Posted by y2k600f4
I'll try not to go into much detail but as some of you may recall I am having the same oil consumption issues on my recent SBC 383 10.5:1 rebuild as I did prior to the rebuild and for the 1st 500 miles I was averaging 1 qt +++ oil useage. The car has been with the builder for 2.5 weeks and it has just had been one ordeal after the other and seems like unrelated items keep braking including a recently replaced lower speedometer cable that failed by melting on exhaust, dipstick tube breaking at block etc (moved to make room for wires). Anyway here is a recap of the items already troubleshooted by the builder.

1. Compression test (185 exactly in all cylinders..no cylinder to cylinder variation)
2. leak down test (good)
3. new viton valve seals for 2nd time (previously changed during rebuild) and valve guides within spec (wanted to rule out heads)
3. PCV (suspect); "temporarily" removed and replaced with dual breather setup...believes it was sucking oil due to incorrect/faulty PCV.
4. new plugs (hot) and wires...old plugs were oil fouled with the worst ones on the driver's side (much more evident).

So far a faulty PVC and bad wires (couple cylinders on driver's side were getting minimum spark) were diagnosed and the latest test drive showed ~1/4 qt of oil consumption in 50-60 miles (about 1/2 as before so progress is being made) with smoke during idle eliminated however it seems like when you rev the throttle you get smoke mostly on the driver's side. One plug was pulled on each side after the test drive...the passenger side is showing the start of a good burn pattern and the driver's side showing some slight oil glazing. Also to note that there is baffles in the valve covers and NO oil residue at all in the breathers even after 600 miles or so, which I would expect the breathers to be drenched with oil with that kind of oil consumption if it was an issue with blowby due to rings/cylinders but I could be wrong.

Anyway to get back to the post subject the next item my builder wants to rule out is the intake sucking oil from the galley. I beleive his plans are to back off the rockers to close the valves, remove the carb and construct a custom plate so to pump compressed air in the intake to observe if there is any leaks in the intake gasket causing oil to be sucked up from the lifter galley.

My question wouldn't that issue been evident when the intake was removed previously ? (I had it off prior to rebuild and back of intake valves had no signs of burn oil, they were bone dry and clean); however when the builder dissasembled before rebuild he noticed inside the intake was oily which was evident when he wiped a clean rag in the intake. I know if you see clouds of blue smoke coming out when engine is revved that it is a sign the intake is "puddling" up oil in high vacuum conditions and it`s not being drawn in until it`s revved. If this is the possible case would it also be evident of oil on back of intake valves and associated deposits ?
08-13-2009 08:00 AM
y2k600f4
Oil consumption due to possible sucking oil from intake valley..signs ?

I'll try not to go into much detail but as some of you may recall I am having the same oil consumption issues on my recent SBC 383 10.5:1 rebuild as I did prior to the rebuild and for the 1st 500 miles I was averaging 1 qt +++ oil useage. The car has been with the builder for 2.5 weeks and it has just had been one ordeal after the other and seems like unrelated items keep braking including a recently replaced lower speedometer cable that failed by melting on exhaust, dipstick tube breaking at block etc (moved to make room for wires). Anyway here is a recap of the items already troubleshooted by the builder.

1. Compression test (185 exactly in all cylinders..no cylinder to cylinder variation)
2. leak down test (good)
3. new viton valve seals for 2nd time (previously changed during rebuild) and valve guides within spec (wanted to rule out heads)
3. PCV (suspect); "temporarily" removed and replaced with dual breather setup...believes it was sucking oil due to incorrect/faulty PCV.
4. new plugs (hot) and wires...old plugs were oil fouled with the worst ones on the driver's side (much more evident).

So far a faulty PVC and bad wires (couple cylinders on driver's side were getting minimum spark) were diagnosed and the latest test drive showed ~1/4 qt of oil consumption in 50-60 miles (about 1/2 as before so progress is being made) with smoke during idle eliminated however it seems like when you rev the throttle you get smoke mostly on the driver's side. One plug was pulled on each side after the test drive...the passenger side is showing the start of a good burn pattern and the driver's side showing some slight oil glazing. Also to note that there is baffles in the valve covers and NO oil residue at all in the breathers even after 600 miles or so, which I would expect the breathers to be drenched with oil with that kind of oil consumption if it was an issue with blowby due to rings/cylinders but I could be wrong.

Anyway to get back to the post subject the next item my builder wants to rule out is the intake sucking oil from the galley. I beleive his plans are to back off the rockers to close the valves, remove the carb and construct a custom plate so to pump compressed air in the intake to observe if there is any leaks in the intake gasket causing oil to be sucked up from the lifter galley.

My question wouldn't that issue been evident when the intake was removed previously ? (I had it off prior to rebuild and back of intake valves had no signs of burn oil, they were bone dry and clean); however when the builder dissasembled before rebuild he noticed inside the intake was oily which was evident when he wiped a clean rag in the intake. I know if you see clouds of blue smoke coming out when engine is revved that it is a sign the intake is "puddling" up oil in high vacuum conditions and it`s not being drawn in until it`s revved. If this is the possible case would it also be evident of oil on back of intake valves and associated deposits ?

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