Mercruiser 5.7 EFI Water in Oil

[alldodge]

I put oil in the fuel filter that was used during the season. Once the engine dies from the 2cycle, I remove the old and put the new one on, making ready for the next season.

Might be using a bit to much oil if it's killing the motor.

Oil will not damage the filter, and as more gas gets mixed with it, it thins out. Do understand why you toss it though

 

[Scott06]

After I run the 2 cycle oil through the filter, i assume i have just ruined its ability to filter the fuel properly. Maybe, I am wrong...

If u need to refog it just unscrew add more oil and use it next year will not hurt the filter

 

[sarnone]

Hello, I want to give an update on my water in oil on my 1998 mercruiser 5.7, GM Vortec V-8 EFI. I originally thought it was riser or risers gaskets causing the problem.
I replaced the riser gaskets, still had the problems. Replaced the risers, exhaust manifolds(26 years old), still had the problem. I noticed the intake manifold was loose, only a few pounds of torque on the front and back bolts and others were a little loose. I Pulled the intake and noticed some compromised areas on the original gasket, not totally conclusive. I was ready to replace the intake gaskets and noticed a drip of rusty sludge coming from between the head and block at the head gasket. Is this possibly a blown head gasket or worse? Should I do both head gaskets? Do I need to check for other cracks like in the head and block? I think this engine has overheated before, cannot remember. See my pictures.

I probably should have done a compression or leak down test from the beginning, but the clues were leading me to less serious solutions.

Thanks for your help.

 

[sarnone]

Sorry, the pictures will not attach...says there is a site server error.

 

[Scott06]

Hello, I want to give an update on my water in oil on my 1998 mercruiser 5.7, GM Vortec V-8 EFI. I originally thought it was riser or risers gaskets causing the problem.
I replaced the riser gaskets, still had the problems. Replaced the risers, exhaust manifolds(26 years old), still had the problem. I noticed the intake manifold was loose, only a few pounds of torque on the front and back bolts and others were a little loose. I Pulled the intake and noticed some compromised areas on the original gasket, not totally conclusive. I was ready to replace the intake gaskets and noticed a drip of rusty sludge coming from between the head and block at the head gasket. Is this possibly a blown head gasket or worse? Should I do both head gaskets? Do I need to check for other cracks like in the head and block? I think this engine has overheated before, cannot remember. See my pictures.

I probably should have done a compression or leak down test from the beginning, but the clues were leading me to less serious solutions.

Thanks for your help.

you could do a cold compression test to see if head gaskets hold. Yes a decent over heat its common to split a head gasket, should see it on a comp test. If you ID low cylinder(s) you could do a leakdown on them to pinpoint source of compression loss.

The bolt torque for vortec intakes is actually pretty low but sounds like the intake was off and not torqued down correctly, easy place to get water into oil. Spend money for good intake gaskets like marine felpro

 

[cyclops222]

I still do not see a checking of flatness of cylinder head surface AND the cylinder block surface ?
If lower Vortec bolt pressures are correct ? Why were so many bolts loose ? Did someone do the ....Double Head gasket fix..... A real looser of a DIY.
Pull it all apart and have a Machinist do it the Machinist way.

 

[sarnone]

you could do a cold compression test to see if head gaskets hold. Yes a decent over heat its common to split a head gasket, should see it on a comp test. If you ID low cylinder(s) you could do a leakdown on them to pinpoint source of compression loss.

The bolt torque for vortec intakes is actually pretty low but sounds like the intake was off and not torqued down correctly, easy place to get water into oil. Spend money for good intake gaskets like marine felpro

Thank you for the reply. Would you typically replace both head gaskets at this point if I have one gasket that is split? Would you do any additional maintenance with the heads off?

Thanks

 

[Lou C]

This can be tricky to figure out. A leaky intake gasket will put water in the oil vis the cam valley but not in the cylinders. A leaky head gasket can put oil in both. To further complicate things a bad HG doesn’t always show up on a compression test. Mine didn’t! I did the clear hose test (hoses that feed the manifolds). If they are leaking you may see bubbles in the cooling water which is combustion gas getting into the cooling water. That’s a pretty sure sign.
So if you have both water in the oil & in the cyls I’d say it’s likely the head gaskets. If not on the cyls you can do a comp test just to see but depending on where the HGs are leaking it may not point to the cause.
If you did have water in the cyls then I’d get ready to remove the cyl heads. This isn’t technically a hard job but getting the cyl head bolts out of a raw water cooled engine can be tough. I had to use an impact gun to get all 26 of them out of my 4.3. Have the heads checked by a machine shop and check the block deck for flatness and clean out all of the cyl head bolt holes with a thread chaser….& carb cleaner & compressed air…
I also like to make sure all the cyl head bolts thread fully into the block before installing the heads. You don’t want to find out that one doesn’t when torquing them down!

 

[Lou C]

Thank you for the reply. Would you typically replace both head gaskets at this point if I have one gasket that is split? Would you do any additional maintenance with the heads off?

Thanks

Do both sides, take heads to a machine shop to check for cracks & maybe do a valve job at the same time.
Mine both had cracks from a bad overheat but amusingly it ran fine with normal compression until I started getting water in the oil & a bit of water in 1 cyl, just a trace of water in the other. I wound up replacing the heads with a pair of remanufactured 4.3 heads & put it back together with Felpro marine gaskets & ARP cyl head bolts. The original head bolts were too rusty from raw water cooling to get accurate torque readings. You also have to use gasket sealer on the threads like OMC/Evinrude gasket sealer or Permatex Aviation sealer.

 

[Scott06]

Thank you for the reply. Would you typically replace both head gaskets at this point if I have one gasket that is split? Would you do any additional maintenance with the heads off?

Thanks

Yes do both if one is bad.

if the heads need to come off I would have a machine shop check them out for straightness (block as well). Have them look through the heads do a valve job if needed and replace seals. Likely they will be ok unless warped but you never know.

Check cam and lifters visually while in there but likely they are fine.

Was there water in the cylinders? Spark plugs and combustion chamber would be clean (steamed) if so

 

[sarnone]

Do both sides, take heads to a machine shop to check for cracks & maybe do a valve job at the same time.
Mine both had cracks from a bad overheat but amusingly it ran fine with normal compression until I started getting water in the oil & a bit of water in 1 cyl, just a trace of water in the other. I wound up replacing the heads with a pair of remanufactured 4.3 heads & put it back together with Felpro marine gaskets & ARP cyl head bolts. The original head bolts were too rusty from raw water cooling to get accurate torque readings. You also have to use gasket sealer on the threads like OMC/Evinrude gasket sealer or Permatex Aviation sealer.

Thank you for the info. I will be pulling the heads soon.

 

[sarnone]

Yes do both if one is bad.

if the heads need to come off I would have a machine shop check them out for straightness (block as well). Have them look through the heads do a valve job if needed and replace seals. Likely they will be ok unless warped but you never know.

Check cam and lifters visually while in there but likely they are fine.

Was there water in the cylinders? Spark plugs and combustion chamber would be clean (steamed) if so

Thank you for the reply. I will give an update after i do more tear down.

 

[cyclops222]

Lou C Does his engine have those famous bolt holes that go into water or oil passages ?

 

[Lou C]

It’s water passages but only some of them however I’d just put sealer on all the bolts. Pretty much a small block Chevy thing but other engines are like that too. The thing that messed up a lot of engines was confusion when the Vortec engines came out. The torque spec for the intake was like half that for the pre Vortec & some of the gaskets just didn’t seal well. Personally I feel that GM made a mistake using plastic based gaskets & reducing the # of bolts from 12 to 8. BTW in my experience intake leaks on the pre Vortec are quite rare.

 

[Lou C]

 

[sarnone]

Sorry, posted to incorrect thread.

 

[sarnone]

UPDATE: Water In Oil
So I pulled the first head and my head gasket is not compromised at all. There is also no steam cleaning on the cylinder head. Now I have not gotten to the other side yet, but I am leaning towards the loose intake. Also, since I tightened the intake before the tear down, there was no water in the exhaust manifold when I took the riser off this time. I am going to check for flatness and do both head gaskets anyways.

QUESTIONS:
1. Does anyone have the procedure for torquing the heads, with the angle measurements and the order?
2. Is it ok to re-use the head bolts?
3. The head bolts on the outer edge right at the block have some kind of sealer on the shank and the underside of the bolt head. Is this some kind of sealer? Do I need to reapply or use something on the threads? What brand or type?

Thank you for all your help.
Sarnone

 

[alldodge]

Unable to post pic so the link list the sequence. The ling also list that all bolts final torque is 65ft lb. Merc manual list different index turn to torque which is different and said to be more accurate

First Pass all bolts 22ft lb

Second pass - note it's turn so many degrees not turn to a certain ft lb
Short Bolt 55 degrees
Medium Bolt 65 degrees
Long Bolt 75 degrees

https://www.gtsparkplugs.com/SBC-Head-Torque-Sequence.html

 

[alldodge]

Head bolts that go into water jackets should have a coating of perfect seal or permatex