7MGE BHG Questions

[Turbosidosis]

Hey Guys

A friend of mine is having some issues with his 7MGE 87 supra. It was leaking oil out of the rear of the motor, so I took off his automatic trans and we replaced the cork oil pan gasket that was used on his rebuild, the rear main, and the rear main backing plate which had a junk paper gasket on it, all with toyota fipg. While we had the oil pan off I noticed that it was very milky towards the front of the motor and behind the lower timing plate. Water in oil milky. There was also milk under the oil cap and he has been losing coolant. There is no smoke from the tail pipe or coolate overflowing so I believe that the only way water can get into the oil on a 7MGE is a BHG. We took off the cam covers and all the oil on the top of the head was milky. It looks like the rebuilder used stock toyota torque on the head bolts because all the intake bolts were tight at 60 ft-lbs. The exhaust bolts were loose at 50 ft-lbs. We took off the head, but I really didn't see any issues with the head gasket. no pushed out areas of the copper indicating a BHG. Is there any way water can get into the oil without a BHG?

He has been running this motor on this stock rebuild without issue for the past 2 years, 10k miles.

I also did a compression check on it.

1 180
2 194
3 180
4 186
5 160 - when added oil, got 250+ psi
6 184

All the numbers are relatively high, I assuming because the head was shaved and a stock gasket was used. When oil was added to the fifth cylinder the compression went way up and when we took the head off, you can see the cross hatching on all the cylinders except that one.

I'm leaving it up to him if he wants to do a full rebuild or just have the head done and check the block. Anyone have recommendations or why we have water in the oil on this motor?

Thank you!

 

[hvyman]

Rings ate prolly toast on that cylinder.

 

[fast427]

If your buddy overheated the engine, he could of cracked the cylinder head which would cause coolant mixing with the oil, but in case, the oil would be a thick brown milkshake. you should check for cracks. Normally, if an engine has coolant mixed with oil, its either a blown head gasket or a cracked head or block. good luck.

 

[bigtimr]

My assumption would be since you can no longer see the cross hatch in number 5 there is a possiblity that coolant is entered that cylinder and has scored the cylinder walls. Have you checked the head with a straight edge to make sure its not warped, its not common but sometimes if you overheat a engine you can warp the head causing coolant to enter the cylinder but yet very little is perceivable on the head gasket. Also as fast said theres always the possiblity of a cracked head or block.
I would definetly get a second opinion on the head gasket and get the head checked, if nothing is obvious I would have the block checked to be sure, hope this helps.

Also i believe on the 7mge that if the cover cracks, you can get coolant in the oil but Im only about 40% sure on that.

 

[BuBBaStuBs]

The motor in my 86.5 is doing the same thing but the valve cover gaskets were bad.