Leaking intake manifold

[steppinstone]

Hello I have a 1988 gulfstream sunvista hi rise on a john deere chassis with a 460 ford motor. Over this past spring while on a trip I found the oil was leaking from the rear and front of the intake manifold. I have purchased all new gasket's and was going to repair while laid up for the winter. The question I have is CAN anti freeze get into the oil from the intake? The reason I ask is I just started the coach to charge battery's and it seemed to be smoking a little bit more then normal so I shut it down and checked the oil and found it milky. Could it be the head gasket? I did over heat the coach on the trip the radiator hose blow out I fixed it on the road topped it all off no anti freeze leak's just oil as stated .Made it back home and just been sitting sense. I am hoping it's just the intake and not the head's..... any help??

[STBRetired]

AutoZone has lots of tools you can "rent" for free. If you don't return them, they charge your credit card. The one here in town does have leak down testers. Those 70K miles were probably pretty rough miles. That 460 works pretty hard lugging that RV around.

[BigRabbitMan]

steppinstone wrote:
When I took the reading's the engine was cold will that give a bad reading? Just curious?

No. What I see is a large difference in your high and low numbers which were all done under the SAME conditions. If a warm or cold engine would change the numbers it would change them all, not just part of them. You have numbers all over the place which tells me that you probably have some valves with variable amounts of burning so it is time to redo the top end before that causes more issues. If a couple of cylinders are not putting out their share it means the others have work harder and performance and mileage go down and wear factors increase.

[steppinstone]

When I took the reading's the engine was cold will that give a bad reading? Just curious?

[rgatijnet1]

Sort of an old school way to test but we used to add some oil through the spark plug hole to the low cylinders. If the compression improved, that was an indication of worn rings. If it did not improve, that was an indication of either a bad valve or a bad head gasket. Either one of which would require head removal.
At 70,000 I doubt if the rings are bad on just two cylinders.

[BigRabbitMan]

Given the miles on your coach and how hard and engine works in a motor home, with those compression numbers I would pull the heads and have them redone. You are half way there already so do the heads the rest of the way. Spoken from experience from my 440 days!

[steppinstone]

rgatijnet1 I disabled the fuel pump, removed the distributor cap and wires, also plugs with throttle wide open. Then started from cylinder #1 thru #8 and those were the # for each of the cylinders. STBRetired The motor has 70,000 I find it hard to beleave a total rebuild, for the buget what is that? the children of mine are constanly robbing my wallet they tell me all the time that's what there here for.I don't have have a leak down tester at the moment but will probably add it to my tool box

[STBRetired]

One other idea. When you have the intake and exhaust manifolds off, run a leak down test on the low cylinders and listen to the exhaust and intake ports. If you can hear escaping air, it is definitely the valves. If not could be head gasket or rings. Also check you radiator for oil. If there is a leak in head gasket between water and oil passages, you will have oil in your antifreeze, If the intake manifold is leaking water through the gasket, you won't. There is no pressurized oil passage in the intake manifold, but it could possibly leak water into the valley where it mixes with the oil.

[STBRetired]

Not to spend more of you money, but if you pull the heads you might as well get a valve job done. Could be a bad valve that is causing the low compression. How many miles on your rig? And what kind of budget do you have? Engine is 28 years old. Might be time for a full rebuild.

[rgatijnet1]

Wide open throttle, all plugs out.

[steppinstone]

well I guess a tear down of the heads are in order. Because from the right side #1 cylinder the reading's are 120 , 110 , 80 , 120 ,and left side # 5 cylinder 130 , 120 , 70 , 110 , that is if I did it right wot.

[rgatijnet1]

If the head bolts have not been loosened, then the compression observed should be accurate.

[steppinstone]

Okay I have a question! if the intake gasket is shot! I know it is because it's leaking oil from the front and back ! Will a compression check be nill ? I mean will it gave an accurate measurement?

[allbrandauto]

pull intake manifold off look at gaskets real good if there is a crack in the gasket you will see it

[rgatijnet1]

As the old saying goes, "water and oil don't mix".
The oil looks milky right now because it is still stirred up from the engine running. Left to sit for any length of time and the water will separate from the oil and can cause rust or corrosion to form inside the engine. I would change it if you plan to let the engine sit for any length of time.