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Clean MAF- Sprung oil leak


Richard S

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I removed the MAF and IAC to clean them. Changed the oil & filter. Then I noticed a serious leak. Never had an oil leak before. It looked exactly as though the transmission pan gasket was leaking in the front. When I jacked up the car, I could see it was engine oil not tranny fluid, and stain on the street is about 2 inches to the front of the oil pan, and about 4 inches to the driver's side of dead center of the car. I looked under, but it is not the pan gasket, the drain plug or filter. What could I have disturbed up top that would leak oil? The only liquid that seems to be involved in the MAF is a water line, but that is not leaking.

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Guest Drake

Check the engine oil level sensor. Mounted almost dead center on front edge of oil pan, with a small electrical connector plugged in. Might have cracked the plastic housing.

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I am thinking this is coming from up higher, Drake. When it was jacked up to have the front tires replaced. I could see the constant dripping from the leading edge of the transmission pan. I was sure in was tranny fluid, except wrong color. I don't think it could run there from the oil level sensor. Chas may be correct, but if so, it is a coincidental issue, going from no leak at all, and then this work, and then a major leak. Chas, do you think the main seal would continue to leak with the engine off. I can park the car on a grade, up or down, and I can come out after 30 minutes and see it has been leaking. My street is asphalt, which will soak up oil. The first day, the stain was probaby 3-4 feet long. Could have been cup, cup and a half of oil. Much slower now, but still a very sudden and disturbing development.

I'm thinking plenum gasket. The latter might explain the over revving problem I was trying to cure in the first place. Having tugged on the MAF to get it off when I was thinking I just needed to clean it, I might have aggravated an intake plenum gasket problem. Over revving seems a little worse. Would it leak oil from that gasket? I think one of the ways to test that theory is to spray starting fluid around the plenum with the engine running to see if it affects the idle. I assume one either gets test results or an explosion.

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I am going to guess that it might be coolant because that is what was disturbed. A trick to determine what is wetting your pavement is to take a piece of white paper and dip into a little puddle that is on the road. It is now a lot easier to determine the exact color of the fluid as it shows up quite well on the paper. Also, coolant will dry up fairly quickly on pavement whereas an oil stain will linger for weeks, months, years! It will continue to drip after the car is shut off as the rad pressure continues to force it out. Hope this helps.

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It sure felt like oil, but coolant with both antifreez and dexcool may have an oily feel to it. I did neglect to mention that I put some dexcool in as summer approaches to keep the car running a bit cooler. Never have used it before. I checked the little coolant pipe that goes into the MAF to see if it was leaking, but could not detect anything. Not sure where on the right side there is coolant in that forward of the pan area. I used a little engine degreaser under the MAF area so I can better tell if there is anything new there. I will get under tomorrow and look very carefully, trying the paper trick to identify the culprit for sure. I certainly like Padgett's comment because I would hate to think the rear main decided to give out at just 80k on a well maintained car.

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Guest daveagain909

could be transmission fluid hard to tell some times, It seems to leak more after the fluid settles, could be in the transmission pan gasket.

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Before I sealed things my Corvair (now replaced by the white car) was like that. Drive daily or even weekly and stayed dry. Let sit for a month and there would be a really slow drip. Apparently it takes quite a few days for the torque converter to drain down to the pan.

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Went out this morning and there does not seem to be a leak. I do notice that there does seem to be some coolant loss because the level in the overlflow is a bit low and I filled it the other day. This really is a mystery as all I did was use carb cleaner and starter fluid to isolate problems as now:

1. The high idle problem seems to have cured itself.

2. The leak seems to have disappeared.

Since the overflow is on the other side of the car, doubt that the expansion tank is the culprit. If it was coolant, still not sure what hose is on the right side.

High idle: My only explanation is that the starter fluid may have softened some gasket cement on the intake plenum and it resealed, if only temporarily. Pretty far fetched, I know.

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Hello Richard: We have to determine exactly what fluid is the culpret or else we are just shooting in the dark. Do not put too much stock in the location of the pavement drip because oil and coolant, particularly if it is an upper engine leak, can travel a convouluted path through valleys, along ridges, etc. before it finally decides to collect and drip. Also, coolant leaks can be especially hard to spot because when the engine is running, the coolant is having a jolly time running all over the place but when you shut the engine off, the leak slows,and may even stop. Now the engine heat is able to dry up any trails pretty quickly making the detective work much harder. Do not rely on the coolant recovery bottle level because if there is a leak, instead of pulling water from the bottle when the system cools, it will pull air through the leak. You have to remove the radiator cap and check level in radiator. It can happen that you have a full recovery bottle but your radiator is way down. Antifreeze is slippery to the touch, so not a good test. It is also easy to smell the sweet odor if your heater core is leaking and fan is blowing it all over the inside of your car, and also easy if it is sitting in a pail, but not quite so easy with only a drop on your fingers or on the pavement. Hope this helps.

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I agree that origins can be very difficult to locate. You do make another good point about the expansion tank. Orginally, though there was a tank and a hose, the radiator had not been drilled out. I finally figured this out because the coolant in the tank was always a little low in the morning. Fixed that several months ago and all was fine. When the leak developed I also noticed that the coolant in the radiator was again 1/4 cup low. Checked this morning, and the radiator is full, expansion a little low. Thus I conclude that there was a coolant leak, and, as you say, the expansino tank was defeated because the system was sucking air. I probably wouldn't be able to isolate the leak unless it resurfaces, or I take it to a shop and have the system pressurized. When I flush/change the coolant, I always add some radiator sealant with the fresh antifreeze. This was done several months ago. Perhaps the sealant kicked in.

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Guest Bobby Valines

First thing I would do is take it to the quarter car wash. Clean the hole engine compartment top and bottom. Try to look for the leak as soon as possible after the engine dryes, this will help before the liquid has a chance to get all over. Oh use carb. cleaner not starting fluid to check for vac. leaks, not quit as flammable, safer.

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Richard, please pardon me for interupting but unless I read your posts incorrectly you have a mix of green antifreeze, dexcool and stop leak in the system right now? If so I would suggest you back up a few steps and drop the antifreeze and discard it. To the best of my knowledge dex cool and green antifreeze are not compatible. In addition, stop leak can plug the tubes in the radiator. So I'd get that stuff out of there as soon as possible.

As to the leak, the 89 3800 has a separate tube for coolant that goes from the intake to the throttle body. Chances are good it has rusted from the inside out and needs to be replaced. This thing is one big PIA to replace and the last replacement we got was not a bolt in fit, the base plate on the engine side had to be ground down a little to fit flush against the intake manifold.

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Well, I spoke too soon; leak's back. It is definately engine oil. Bobby, I tend to keep things pretty clean, particularly the top. I am confident it is not coming from the top end, valve covers and the like. The starter fluid spray test proved negative, and in cany case, there is no evidence the leak is coming from the intake plenum. I am now drifting back to the horrific idea that it might be a coincidental failure of the rear seal. I doubt that running Valvolene 20/50 would have blown the seal. I just can't think of that many places on the left side of the car that oil could leak from. I did remove the plastic flywheel cover the other day and saw some oil on it in side and an out, though nothing on the flywheel. Course I didn't reach all around it, either. Right now I have it parked on a slant driver to passenger. If the leak was making its way from left to right, this should negate that and I should see the drip move to the right.

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I am glad that you have determined that it is an oil leak. You mentioned in your first post that you had changed the oil and filter with 20W50. Is this what was in it before? Did the leak start after installing this oil? If so, I would change back to the factory recommended fill. 20W50 should not hurt????, but again should not be necessary, either. A short story - I had a 1983 Caprice wagon, 305, with about 90,000mi on it. Ran perfect and decided to pull a small trailer. I thought that I would be smart and add some extra protection for pulling and installed 20W50. After that, I pulled the trailer a couple of times and had overheating only with the trailer. Checked cooling system over from top to bottom and could find no problem. Did not overheat yesterday, overheats today... what has changed??? After much head scratching, the only thing that I had done was the heavier oil. Changed back to 10W30, problem gone. Never came back for as long as I had the car. Now, I have no explanation for this but I cannot deny the evidence. Strange things can sometimes happen!!!

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Yes it can. It was 82 near the coast here in SD today; much hotter inland. I have always run 20/50 in all my cars here without incident. But you could be right. Before I change weights, I probably should take it to a pro with a lift and see what he says.

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I have run hundreds of thousands of miles on 10W30 (feel Florida weather does not need 5W30), would be a little concerned about the time for cold 20W50 to get through some of the tiny passages. Only time I had an oiling issue was when the family car dropped two cam bearings in the bottom of the pan.

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Richard: If it had 20W50 in it before, I guess that idea is blown out of the window. I have always been a firm believer that if a machine was working, was monkeyed with by me and now doesn't function, it was most likely something that I did...it has happened to myself. Ouch! Self confessions always hurt! You are to the point now that long distance help is becoming difficult and a rack inspection is your best next step.

Pagett: You are correct. Engines, amoung other things, are built to much closer tolerances than the flat head Dodges of yesterday,(no slight to Dodge, thats just the way it was) because of better machining practices, materials and the quest for the cockpit to be dead quiet. These tighter tolerances only become closer when an engine is hot so the days of thick oil being of much benefit is a good point to argue about in miles of internet threads, only, in my humble opinion.

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Guest daveagain909

what is the correct oil weight to use? I think it would be helpful if we new this by geographic area? florida or south east, north east, central usa, southern california? or?

ANY RECOMMENDATIONS? THIS WOULD BE VERY HELPFUL?

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I would use 5w30 below 0C and 10w30 above for a good engine. The georotor pump used in the 3800 is really quite stable.

Have used 10w40 in worn and 20w50 in really worn chevvys with gear pumps and straight 30 racing oil for competition.

The guideline seems to be 10psi for every 1000 rpm and the Power book said not to exceed 65 psi.

Personally think that regular premium oil and filter changes are more important than the weight. Have not yet decided if "High Milage" oils are worth about a buck more per gallon or not.

Good write up here.

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DAVES89: You are right on the money. Follow the owners manual and you cannot go wrong. I sometimes have to laugh... the internet is swimming with oil discussions ad nausium when in fact, oil related engine wear/failure disappeared about 50yrs. ago.( sludge problems excepted) I can remember when cars got up there in miles, the engines got noisy, might smoke a little and maybe even a knock or two. British cars came right from the factory with the smoke! It is rare now to actually wear out an engine. I have been in boneyards where motors have had the heads removed and the cylinders show no wear; they look like new inside. Its the other stuff - transmissions, wiper motors, door handles, window motors, cheap plastic junk that seems to do a car in before you have an oil burner. Being anal about brands, types, viscosities, oil filter brands, changing once a month etc. does not seem to buy you much. Follow the owners manual, and you will be golden. The other stuff will git you before the engine does! Now, coolant getting into the oil, aka. GM 3.4l , that is a different story.....

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I used to go out to the desert pretty often. With temps over 100 and the a/c blasting, engine temps were pretty high. Hence the 20/50. Since I bought in case lots when it was on sale, and that weight cost no more than any other, I've just stuck with it for no apparent reason. Now is the 3.4 you refer to the very twin cam I have in my 93 Cutlass Supreme convert? Does it explain why that engine had so few applications and came and went so quickly?

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Chevrolet Power Book. Grew out of the green loose-leaf pages that Vince Piggins and his crew used to send out to racers. Mostly tips, specifications, and part numbers on how to build a race engine.

Chevvy 2.8/3.1/3.4 had various derivatives one of which was the Twin Double Overhead Cam version of the early 90s. If anything like the the Quad Four, it is a nightmare to assemble correctly. Like all iron block engines at GM, it is obsolete.

Overhead cams make for a very pretty and high winding (but not as high as a desmo) engine which is great for racing & quick changes but of limited use otherwise.

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Do you really think that the auto makers are going make an engine, or for that matter any part that will last forever? They build cars that have expiration dates. They are built to wear out. Now in the same venue, do you think they are going give you the exact correct information on how to keep the engine, or part working forever? My point being, that if you believe everything they tell you, you will be purchasing a new car regularly. That is why I don’t believe the optimum oil pressure is only 60 lbs. That is old tech.

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It depends on the design (and getting quite far off topic). All I can say is that my experience with engines is that with proper care a good design can last a very long time.

In 1970, a car with 100,000 miles was considered to be worn out. Certain designs were just bad (first examples of Chevvy 350 and Pontiac 455 lost cranks right and left. In both cases the crank bearing area was increased and they became very reliable).

The 1973 455SD was very reliable. It was also the only GM engine I ever saw designed for 80 psi oil pressure and it had special bearings, a special oil pump, and a special distributer with a bigger hardened drive gear (oil pump was driven by distributer). The package must be designed to support it.

I was told by a bearing engineer that too high oil pressure could damage production bearings. I know that increasing oil pressure and increasing the viscosity (weight) of the oil increases the drag on the engine. Also was told that the most wear was on startup and the key was to get oil everywhere quickly.

In racing engines I used straight 30 weight synthetic oil to get a little more power. For street use, 10w30 dino goes in (I change oil to remove contaminants too often to justfy sysnthetic). Lately I have been buying "high mileage" oil for the extra additives.

Really, the pressure is irrelevant. More important is having the film of oil on all plain bearing surfaces, the pressure just gets it there and volume is really more important.

Modern engines are designed to be "tight" with much smaller clearances than we used in the 60s.

My experience is that the 3800 is a very reliable engine and the iron block & lack of VVT are the reasons it is being replaced. Maybe it is just too reliable.

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You actually think that 10w30 at 60lbs pressure can stand up to rod bearing pressures at 5500 rpm? Don't you think that 70 or 80lbs oil perssure could bo a b etter job.

I know for a fact from building drag racing engines that with an increased oil pressure the engines lasted beyond expectations.

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Richard: The 3.4 of which I speak is installed in 1997? and up to fairly recently GM minivans, larger front drive cars. As to the oil, you have had success with it, so I see no need to change. It was just a guess on my part to trace your leak.

63Viking: There are always exceptions for purpose built engines, but the selection of oil pressures has to satisfy many needs to be effective:

1. Enough pressure to satisfy all lubrication needs at ALL temperatures.

2. Keep drag down that high pressures produce.

3. High pressures may tend to wash out bearing material in factory installed units.

4. High pressure may flood cylinder walls resulting in emissions going for a tail spin and oil consumption.

5. Many other considerations.

Anyways, we digress. I still maintain that there are millions of vehicles running around following manufacturers guidelines, or worse, with 10W30 oil and Fram filters that live long and healthy lives while everything else that surrounds the long block either cracks, smokes, crumbles and otherwise blows up. Its the other stuff that will "git ya".

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We've had this oil pressure discussion before. It is not extreme oil pressure that is needed in racing engines. What is needed is a high volume of oil flowing through the engine that cools the bearings. Good engine builders build the engines with a lot of clearance between the bearing and the crankshaft journals so the oil will easily flow out. Then they add a high volume oil pump in order to maintain oil pressure with the extra volume of oil going through the system.

Simply increasing the tension of the relief spring on the oil pump is not the proper way to go about making a high horsepower, high RPM engine last longer. Granted, it may be better than doing nothing but the high pressure is going to rob horsepower by increasing the power that is needed to turn the oil pump. Increasing the pressure only increases the volume of oil going through the engine slightly and does not do much to help cool the bearings.

Heat is usually the cause of bearing failure in an engine under load. Keep in mind, there is no water flowing through the crankshaft, rods or saddles in the block where the crankshaft is mounted to cool the bearings. The oil flowing through those parts is what keeps them cool.

Also, high oil pressures increase the chance of failure of other parts like the shaft between the distributor and oil pump (if is is driven that way), the oil filter and seals in the engine.

In most applications, the proper way to lubricate a high performance engine is by maintaining high flow volume and moderate oil pressure. When the engine is warmed up, 25-40 psi at idle and 50-60 psi at high RPM is what most of the engine builders that I know shoot for. Straight 40 weight Valvoline is usually the oil of choice for them.

BTW, If you are really concerned about you racing engine you need to have an AcuSump or similar system that will supply pressurized oil to the engine before it is started. That is the best thing you can do for your engine to make it last after you have proper flow and pressure taken car of.

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