sporadic oil in water problem, sbc, rebuilt motors
11-14-2012, 11:39 AM
#1
sporadic oil in water problem, sbc, rebuilt motors
Background: This is a summary of several post that were in my rebuild thread in the formula section as background to my “issue”. I am redoing a 1986 Formula 272 LS. Put in rebuilt truck motors from the 97 to 99 model year with vortec heads and stock mercruiser cams (295 – 300 hp models). The Starboard motor had a spun bearing, so the crank and block were cleaned and magnafluxed. Crank turned and the bores power honed and put back together with new bearings, rings, cam, etc. This is the motor that is getting water in it. Motor has been run several times on the hose tuning everything in and testing, never a problem with water.
On 9-13 we took it out for its first maiden run on a lake and everything worked well, ran about ˝ an hour. We went through all the fluids and starboard motor oil was high and milky!!!! Upon inspection, you could see the brown foam along the intake manifold - head joint. So we figured the intake didn't seal on that side so we pulled it off and redid it. Changed oil and ran it on the hose for a bit, all seemed good.
September 26th , second run around the lake for awhile going slow and medium speed, never really into the secondary’s. Stopped on the water at one point and checked the oil again and some foam again on the dipstick and a bit on top of the intake manifold. Well, after looking at it, oil didn't look like it was over filled, so I was thinking it was still burning off residual water. We ran it around some more with a light load on it watching the motor. Steam was coming out of the breather tubes and condensing on the flame arrestor to drip onto the intake manifold, so that made me feel better that the intake wasn't leaking again. The more we ran it, the clearer the oil got and by the time we were done, it looked brand new again with the boat back on the trailer. After cooling down and sitting, oil still looked perfect and at the correct level.
October 25th. We went for the third and last run of the year. Had problems with the fuel pump again (separate issue) so we were being towed in after running for 20 to 30 minutes. When we opened the engine cover to work on fuel pump, we saw the starboard motor was foaming again. Got the boat back on the trailer and back to the shop for inspection the next day. Once things had a chance to cool and settle down, doesn't look as bad as I originally feared.
The Starboard motor water leak is pretty much a complete repeat of the first time it took on water. Oil level is about 1/4 to 1/2 quart high and has the brown water look to it. It didn't cook it real bad as the water separated out floating on top. Oil looked clean when we checked it the next morning. Then we did a compression check on the motor and it read at 150 psi on all the cylinders. Checking the oil again, it was stirred up and you could see the brown. So water is in it, but must not of been in too long. Maybe I got a bad intake manifold that is not sealing properly?
I thought I remembered seeing the SB motor with more foam on top of it, but we were drifting at that point, so not sure. Here is a picture of the SB motor with some of the settled foam that dripped off the cold flame arrestor onto the manifold and the oil in the bilge back in the shop (separate issue from other motor).
Today: November 14. Motor is out and on the stand but still all together from the pan to the carb with exhaust still on. I made up four plugs to plug the four hoses going to the exhaust manifolds and risers. I then made a plug for the cooling hose from the outdrive with a pipe tap in it so we could hook up a regulator and valve. this allowed us to hook up an air hose, set it to 6 psi and then shut the valve isolating the engine from the shop air.
The damn thing has held perfect pressure now for 1/2 an hour! Two and a half hours later the block is still holding 5 psi of air, so has lost 1 psi. I would think if it was a cracked head or bad valve guides it would leak air all the time. So now I am back to thinking it is the intake manifold gasket letting go when the engine gets up to temperature. (Note: this is also the engine without a working temp gauge. We used a thermocouple for the first run in the thermostat outlet and the motor temp seemed fine, but did want to throw this out there.)
I was hoping for some hissing sounds that we could pinpoint. Nothing is heard even with a stethoscope. Of course, holding 6 psi would not expect to hear anything. Kinda stumped on this motor now.
At the least, I will change out the intake manifold gasket and inspect the mating surfaces. Still going to pull the pan and inspect the bearings also since it is out of the boat.
So, any test to do or areas to concentrate on?
Brian
On 9-13 we took it out for its first maiden run on a lake and everything worked well, ran about ˝ an hour. We went through all the fluids and starboard motor oil was high and milky!!!! Upon inspection, you could see the brown foam along the intake manifold - head joint. So we figured the intake didn't seal on that side so we pulled it off and redid it. Changed oil and ran it on the hose for a bit, all seemed good.
September 26th , second run around the lake for awhile going slow and medium speed, never really into the secondary’s. Stopped on the water at one point and checked the oil again and some foam again on the dipstick and a bit on top of the intake manifold. Well, after looking at it, oil didn't look like it was over filled, so I was thinking it was still burning off residual water. We ran it around some more with a light load on it watching the motor. Steam was coming out of the breather tubes and condensing on the flame arrestor to drip onto the intake manifold, so that made me feel better that the intake wasn't leaking again. The more we ran it, the clearer the oil got and by the time we were done, it looked brand new again with the boat back on the trailer. After cooling down and sitting, oil still looked perfect and at the correct level.
October 25th. We went for the third and last run of the year. Had problems with the fuel pump again (separate issue) so we were being towed in after running for 20 to 30 minutes. When we opened the engine cover to work on fuel pump, we saw the starboard motor was foaming again. Got the boat back on the trailer and back to the shop for inspection the next day. Once things had a chance to cool and settle down, doesn't look as bad as I originally feared.
The Starboard motor water leak is pretty much a complete repeat of the first time it took on water. Oil level is about 1/4 to 1/2 quart high and has the brown water look to it. It didn't cook it real bad as the water separated out floating on top. Oil looked clean when we checked it the next morning. Then we did a compression check on the motor and it read at 150 psi on all the cylinders. Checking the oil again, it was stirred up and you could see the brown. So water is in it, but must not of been in too long. Maybe I got a bad intake manifold that is not sealing properly?
I thought I remembered seeing the SB motor with more foam on top of it, but we were drifting at that point, so not sure. Here is a picture of the SB motor with some of the settled foam that dripped off the cold flame arrestor onto the manifold and the oil in the bilge back in the shop (separate issue from other motor).
Today: November 14. Motor is out and on the stand but still all together from the pan to the carb with exhaust still on. I made up four plugs to plug the four hoses going to the exhaust manifolds and risers. I then made a plug for the cooling hose from the outdrive with a pipe tap in it so we could hook up a regulator and valve. this allowed us to hook up an air hose, set it to 6 psi and then shut the valve isolating the engine from the shop air.
The damn thing has held perfect pressure now for 1/2 an hour! Two and a half hours later the block is still holding 5 psi of air, so has lost 1 psi. I would think if it was a cracked head or bad valve guides it would leak air all the time. So now I am back to thinking it is the intake manifold gasket letting go when the engine gets up to temperature. (Note: this is also the engine without a working temp gauge. We used a thermocouple for the first run in the thermostat outlet and the motor temp seemed fine, but did want to throw this out there.)
I was hoping for some hissing sounds that we could pinpoint. Nothing is heard even with a stethoscope. Of course, holding 6 psi would not expect to hear anything. Kinda stumped on this motor now.
At the least, I will change out the intake manifold gasket and inspect the mating surfaces. Still going to pull the pan and inspect the bearings also since it is out of the boat.
So, any test to do or areas to concentrate on?
Brian
11-14-2012, 12:18 PM
#3
VIP Member
I know almost nothing about rebuilding engines except what a shop told me about the milling of block and heads. If you had the heads and block milled, then the intake should be milled also to match up water jackets perfectly. I don't know if this is the case in SBC vs BBC. just a thought.
11-14-2012, 02:47 PM
#4
Plugs looked pretty good. I didn't pull them, mechanic here did. I saw a couple of them and they seemed fine. I will look at them all again and see if I see any differences.
No oil cooler on these SBC's. Only heat exchanger is the power steering one.
Not sure on BBC vs. SBC. But these are bone stock automotive engines. Surfaces looked good. We ran a stone over them and made sure we got any knicks out of them before hand so they had a good surface to seal to. Same with the heads and the intake manifolds are brand new. So no machined surfaces on only one part causing a mismatch height on the manifolds. At 300 HP these are not high performance motors, pretty much stock chevy stuff with a carb.
First run ended with water, redid intake manifold.
Second run ended without water, oil system ended clean.
Third run ended with water. I am leaning towards a bad gasket, but really wanted to ask first. Might be a bad intake manifold also that is marginally sealing.
Brian
No oil cooler on these SBC's. Only heat exchanger is the power steering one.
Not sure on BBC vs. SBC. But these are bone stock automotive engines. Surfaces looked good. We ran a stone over them and made sure we got any knicks out of them before hand so they had a good surface to seal to. Same with the heads and the intake manifolds are brand new. So no machined surfaces on only one part causing a mismatch height on the manifolds. At 300 HP these are not high performance motors, pretty much stock chevy stuff with a carb.
First run ended with water, redid intake manifold.
Second run ended without water, oil system ended clean.
Third run ended with water. I am leaning towards a bad gasket, but really wanted to ask first. Might be a bad intake manifold also that is marginally sealing.
Brian
Last edited by befu; 11-14-2012 at 02:52 PM.
11-15-2012, 12:24 AM
#6
Registered
iTrader: (2)
Join Date: Aug 2005
Location: Between A Womans Leggs in IL
Posts: 6,306
Likes: 0
Received 1 Like
on
1 Post
Just have to ask,,did you seal all the head bolts?? Loosen all the rockers,,put 150 psi of air in each cylinder..remove the caps on the water ports and see if air is comimg out..may only be leaking when hot or under alot of pressure..
11-16-2012, 02:54 PM
#8
Alright, so we take pressure up to 20 psi and all we get is some air leaking from the hoses on the thermostat housing were it did not leak water before. So now with 20psi in it, it will leak down but it still is real slow. nothing that seems to indicate taking on that much water in 10 to 20 minutes of idle mild running.
So, we filled the engine up with water and hooked it up with 14psi regulated air. Left the oil pan plug open with a clean bucket under it and left for the weekend. We will see if there is anything in the bucket after 3 days at 14psi.
Galley will be checked when we remove the intake manifold. This block was magnafluxed also.
We are going to look at the head bolts next week and do the cyclinder pressure test. The head gasket should prevent any cyclinder pressure from touching the bolt though. I thought he bolt holes, if they went all the way through, would be into the water jackets. So it would still be from the cooling passage into the rocker arm area under the vavle covers. will have to look at a spare engine. All the cylinders had good pressure at 150psi +/- a few.
Will look at exhaust manifolds, but the plugs all look really good. And why would it leak the first and third time but not the second?
brian
So, we filled the engine up with water and hooked it up with 14psi regulated air. Left the oil pan plug open with a clean bucket under it and left for the weekend. We will see if there is anything in the bucket after 3 days at 14psi.
Galley will be checked when we remove the intake manifold. This block was magnafluxed also.
We are going to look at the head bolts next week and do the cyclinder pressure test. The head gasket should prevent any cyclinder pressure from touching the bolt though. I thought he bolt holes, if they went all the way through, would be into the water jackets. So it would still be from the cooling passage into the rocker arm area under the vavle covers. will have to look at a spare engine. All the cylinders had good pressure at 150psi +/- a few.
Will look at exhaust manifolds, but the plugs all look really good. And why would it leak the first and third time but not the second?
brian
11-16-2012, 05:30 PM
#9
Registered
iTrader: (2)
Join Date: Aug 2005
Location: Between A Womans Leggs in IL
Posts: 6,306
Likes: 0
Received 1 Like
on
1 Post
fixx
Alright, so we take pressure up to 20 psi and all we get is some air leaking from the hoses on the thermostat housing were it did not leak water before. So now with 20psi in it, it will leak down but it still is real slow. nothing that seems to indicate taking on that much water in 10 to 20 minutes of idle mild running.
So, we filled the engine up with water and hooked it up with 14psi regulated air. Left the oil pan plug open with a clean bucket under it and left for the weekend. We will see if there is anything in the bucket after 3 days at 14psi.
Galley will be checked when we remove the intake manifold. This block was magnafluxed also.
We are going to look at the head bolts next week and do the cyclinder pressure test. The head gasket should prevent any cyclinder pressure from touching the bolt though. I thought he bolt holes, if they went all the way through, would be into the water jackets. So it would still be from the cooling passage into the rocker arm area under the vavle covers. will have to look at a spare engine. All the cylinders had good pressure at 150psi +/- a few.
Will look at exhaust manifolds, but the plugs all look really good. And why would it leak the first and third time but not the second?
brian
So, we filled the engine up with water and hooked it up with 14psi regulated air. Left the oil pan plug open with a clean bucket under it and left for the weekend. We will see if there is anything in the bucket after 3 days at 14psi.
Galley will be checked when we remove the intake manifold. This block was magnafluxed also.
We are going to look at the head bolts next week and do the cyclinder pressure test. The head gasket should prevent any cyclinder pressure from touching the bolt though. I thought he bolt holes, if they went all the way through, would be into the water jackets. So it would still be from the cooling passage into the rocker arm area under the vavle covers. will have to look at a spare engine. All the cylinders had good pressure at 150psi +/- a few.
Will look at exhaust manifolds, but the plugs all look really good. And why would it leak the first and third time but not the second?
brian
11-16-2012, 06:51 PM
#10
if you did not seal the head bolts which i think you did not from what you said then thats your problem,,it gets hot and they start leaking,,all SBC head bolt holes are wet so they require thread sealer..just take one out at a time and seal them off then retorque,,repete.and repete torquing again..
Brian
