Maddening 3 Year Oil In Intake Mystery!! Long, sorry..

LarryH

Registered User
Gents, I have been attempting to find a problem in what I believe is a leak in the intake manifold causing fouled plugs for approaching 3 years and am at wits end. The motor has been heavily modified and the heads and block have been cut a couple of times each which required the intake manifold to be cut as well.

However the plugs are fouling and the intake is definately very damp with oil upon inspection. After a couple of years of tryinng on and off to diagnose the problem, I finally gave up and took the motor to a very reluctant Kroyer's Racing at the Las vegas Speedway. They are an award winning Nascar engine builder. They mocked the motor and said that the intake manifold was binding on the bolts slightly which required them to bore the intake bolt holes. After which, they concluded that the intake manifold was cut well and fits the head valley well. They also confirmed that the heads and block were cut straight. Unfortunately, upon reassembly and start up - same problem. Now, they are not interested in an easter egg hunt and have asked that I go elsewhere for solution.

The PVC system has been modified to simply loop the passenger crankase through a filter and back into the plenum and the driver side vents to atmosphere. The filter in the loop is not wet so we are fairly confident that it is not coming from the crancase. Additionally, the lower end of the motor is new so blow by is fairly assumed to be negligible, if any. The other symptom seems to be that under boost the plugs seem to clear a bit and then after lengthy idle (i.e. vacuum) the plugs foul again. This would seem to also support galley oil being pulled into the intake.

Intake has been assembled 4-5X so assembly error is highly unlikely. Heads are new and have been tested for leaks and nothing. Don't see it being the valve stem seals as it should pull the oil into that cylinder and not through the entire intake.

QUESTION: we feel the next step is to either put a vaccuum or charge on the intake and attempt to diagnose leak that way. Motor is currently on stand. Anybody done this?

QUESTION; how else would oil get into the intake if we assume it is not coming from crankcase ventilation????

I don't want to give up here as the motor has been heavily upgraded with h beam rods, diamond pistons, stud girdle, tons of aligning and balancing work at Kroyers, valves, porting, etc, etc, etc,. Nonetheless, this has been one of the most frustrating experiences of my 42 year existence.

Any help, please.

Larry
 
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I assume they have been fouled out by oil from the title. I would put a filter in the PCV line, but there would probably still be some oil makin it through from the blow by. Sounds like you need a fresh rebuild.

Chris
 
Very interesting problem ...I feel your problem lies in your PVC setup ...and venting to atmosphere...on the one side ...the PVC system is a closed loop system.. between the crankcase and both right rocker[PVC valve] and left rocker{vent } both with 2 different vacuum supply ports ..designed to run under vacuum ..when under vacuum conditions like at idle....now the block/crankcase is a open loop ... with the venting of the one side ... no vacuum can be supplied to the crankcase or rocker covers ..but there is still a vacuum draw at the PVC valve ...and think it is drawing your oil in to the system...like a straw.....due to no negative pressure in the crankcase ..when called for ....that being said ..a stock setup still will circulate oil through out the intake system ..but shouldn’t foul plugs ....dave
 
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I think it's the PCV valve set up, that is allowing oil into the intake manifold. Suggest disconnecting it entirely and putting a breather vent in each rocker cover to see if that corrects the problem.

If your not ready to give up on the PVC system. Go to Ford and buy the correct PCV valve and breather. Hook a hose up from the breather (driver's side rocker cover) to the air intake tube (between MAF and TB). Install an oil seperator between the PCV valve and where the hose attaches to the inlet plenum just past the TB.

It would have to be putting a fairly large volume of oil into the manifold to cause it to foul out the plugs. I've got an inline fuel filter on mine and it still gets a lot of oil into the intake from the PCV valve. Sometimes a couple of my plugs get fouled and motor feels stumbly at startup and it blows a big cloud of oil smoke out the tail pipes...but that usually clears up within a few seconds. Not sure if it's from oil in the intake or leaking valve stem seals.

I've also found that running a heavier oil reduces the amount of oil that gets into the intake from the PCV valve. I'm using Valvoline 20w50 except for winter then switch to 15w40.

David

PS: Are you sure it's oil fouling the plugs and not excessive fuel ? I once had a leaky fuel pressure regulator (leaked fuel thru vacuum hose) and that fouled the plugs as quick as I could install them. It was only a problem at idle.
 
Dave and Dave,
thank you so much for your replies. We are quite confident that it is not the PVC system as, i believe, a couple of things would have to be present: 1) the inline filter in the looped pvc system on the passenger side would have to be quite contaminated since the plugs are fouling within 100 miles or less, 2) blow by would have to be pretty severe to dump enough oil into the system to foul plugs that quickly.

Also, this system of looping the passenger side with an inline filter has been employed countless times with no resulting issues. Indeed, it has been on this particular car PRIOR to the motor upgrade with no issues whatsoever.

Dave N. the unfortunate thing I must admit is that we never did disconnect the PVC system entirely due to our confidence that the PVC system was not the issue. I know, I know, never ASSUME. Nonetheless, every indication points to something else. At this point, the motor is on a stand.

Other than a leaking intake manifold gasket and blow by entering through the PVC, is there any other way oil can get into the intake manifold?

PS, definately oil, not fuel

Thanks again!!!
Larry
 
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Larry,

To determine if the oil is coming from the PCV system, loosen the lower IC tube where it connects to the intercooler. This is the lowest point in the intake system prior to the manifold and where most of the oil from the PCV system will collect. If there is oil in this area it could only come from the PCV system or an internal leak on the supercharger. It's normal for an ounce of oil to leak out the connection. How much oil present depends on how long it's been since the tube was last removed and how worn the motor is.

Fresh motors can actually have more blowby than one with 30k miles on it. The amount of oil coming into the motor from the PCV valve isn't directly related to blow by. Even on a perfectly good motor you will still get alot of oil.

I'm also curious what spark plugs and motor oil your using.

David

PS: If the PVC valve is stuck open or isn't the correct valve, it can draw a lot of oil into the intake.
 
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I don't have near the experience that some guys (who already posted) have, but here is my 2 cents worth anyway :) .

First, the PCV system is designed to remove nasty gasses, but it also serves to provide a partial vacuum in the crankcase and this aids piston ring seal. Further, The drivers side is the fresh air inlet, and normally it gets its air from the intake tube after the MAF and air filter. All you're doing with your setup is allowing un-metered dirty air to enter the engine crankcase... not good.

Second is your spark plugs. If the heat range is too cold, fouling will result. If you're using colder-than-normal plugs like so many do, put the OE extended-tip plugs back in for a short period and then pull them out to "read" them.

Third, what thermostat are you using? 160? This may be too cold for your engine and you may never reach adequate operating temperatures (which would also promote plug fouling).
 
Okay. After reading through all of that, the only thing it can be with the exception of the PCV is the rings. If they are all lined up or installed upside down, they can allow the oil to blow by, and in fact will promote this. If you are not getting oil into the filter for the PCV than your problem is elsewhere. Is there a possibility that the drain back holes are blocked from an improperly installed HG that is making all of the oil stay on top of the head? If that is the case, than no matter how good your valve seats are, you are going to get a fouled out plug. Also, from the reading, it leads me to believe that ALL of the plugs are fouling. Is this the case? If so, is your ignition system up to snuff? Are you getting blue spark? Pull the valve cover off of one side and see if the oil drains at the rear of the head as it is supposed to.

Chris
 
Who did the bottom end? What kind of rings did you use? What was the final hone? What kind of break in was the engine subjected to?

Have you had the intake checked for a fracture?
 
Valve stem seals? I only say this because I'm currently replacing oil fouled plugs every 3 months in my sons 4.6 crown vic due to bad valve stem seals. Just haven't had time since he bought the car (with the parts to do the job) to pull the heads and do the work.
 
Thanks for the discussion!

Dave, there was some oil in the intercooler. I would say a slight more than expected but not too much. I have certainly seen more. We have been using straight 30W for break in and the plugs are the OEM autolites. The oil in the PVC, where would it be coming from if it is not blowby? If it is coming from the PVC, then something is horribly wrong because it is fouling plugs within 50 miles of break in. The plugs are wet and when the intake is inspected by removing the plenum and passing your hand through the inside of the manifold, your fingers come out wet as well. Also, for that much oil, wouldn't the little inline filter be soaked pretty good? It seems pretty clean.

Paul, the dirvers side valve cover breather is filtered so that shouldn't be a problem and the thermostat is 180.

Chris, the rings are sealed power chromoly and Kroyer's built the bottom end. These guys are very, very meticulous. Their shop is well known on the west coast and it was purely out of sympathy that they even took the job. The bottom end was built 2x during this escapade and we still had the same problem. I am confident that the rings are in good shape. HG is the MLS steel and the surfaces have been mirror finished. Intall on them is good also as they have been done twice as well with same result on plugs. 4 of the 6 plugs were clearly oil fouled and the other 2 were burning pretty decent.

Question: How do you check aluminum for fracture? I understand that you can't magnaflux it. I am still leaning towards a leak in the manifold that is allowing oil to be pulled up during vacuum. Recall that the plugs and idle seem to improve after heavy boost (i.e. no vacuum so oil is not being pulled through from the galley).

Question: with long block on engine stand, how can i charge or vacuum the intake to check for leak?
 
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Question: with long block on engine stand, how can i charge or vacuum the intake to check for leak?

Victor at spinningwheels-sc.com sells a "pressurized vacuum tester". It somehow seals the intake and then you can pressurize the entire system.
 
Did they mirror polish the cyls for the chromoly rings? There is a different process for regular and chromoly. If they used a regular hatch stone on the cyl walls, they have chewed grooves in the rings. Also, are all of the ring gaps in line? How many miles are you going with the break in? How many miles are on the rebuild? Did you get different rings with each build and did the builder know that they were chromoly? I do not see how you could get enough oil from the valley to soak the plugs in 4cyls unless you could SEE a crack in the valley pan. Worse case scenerio (sp), put a coat of sealant spray on the bottom and RTV over the cap. I still think there is something else.

Chris
 
Chris,
I have to assume (again sometimes scary but I think safe here) based on who this engine builder is, that they knew exactly what the rings were and that the hone and end gaps were executed meticulously. The rings were replaced with both rebuilds with the same result. Went 250 miles last time and about 75 this time. Same result.

QUESTION: even ona new motor, is it typical to foul plugs during break in?

thanks!
Larry
 
Chris,
I have to assume (again sometimes scary but I think safe here) based on who this engine builder is, that they knew exactly what the rings were and that the hone and end gaps were executed meticulously. The rings were replaced with both rebuilds with the same result. Went 250 miles last time and about 75 this time. Same result.

QUESTION: even ona new motor, is it typical to foul plugs during break in?

thanks!
Larry

It is not normal to foul plugs. Ever. Especially stock plugs.

Check your intake and intake ports for leaks. You don't need to buy anything fancy to do it. Just back off the rocker arms so the valves are all closed, cap off the bypass, and make or buy an end cap for the IC tube connection. I cut up an old IC tube, welded it shut, and added an air hose nipple to it. That way you can easily pressurize the system to any psi you want. I wouldn't go over 30psi.

I don't know what you guys consider "normal" for oil in the system but on a fresh rebuild like that there shouldn't really be any. I just completed about 10 6000rpm WOT dyno pulls and put about 100 street miles on a brand new motor and when I pulled the blower and IC tubes off they were essentially dry. It has a stock PCV system on it with a motorcraft PCV valve and no other filters or vents.

BTW, Sealed Power rings are ductile iron with a plasma moly barrel face. Not chrome moly. Chrome faced rings are not chrome moly, chrome faced rings are typically either stainless steel or a similar alloy with literally a chrome barrel face on them.

I'm sure the shop knew what they were doing and this problem is something unusual and up to now, undetected. I do not suspect improper use or assembly but rather something very wrong that has been overlooked or missed becuase of people being unfamiliar with some of the problems inherent in building these motors.
 
Dave,
thanks for the correction. The rings are indeed moly and I am abundantly familiar with that but not thinking clearly. Ok, so the best course of action now is to pressurize the system.

Question: The heads have been pressure checked by Kroyer's and all was certified good. I have a leak down tester that I can use to limit the pressure but should I expect some leakdown as a result of the valves not being a perfect air seal?

Thanks a million,

Larry
 
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