Wish that thread was around a few years ago when I was going through the oil temp. Great info!!

Firewalker, if you decide to get a bigger pan, good idea to check and make sure there are no cross members or other obstructions in the bilge that will interfere with a bigger pan.

Pay close attention to Tom Cats post #22, It is imparitive that you reserch the inblock oil bypass valving for it is different if you go with a remote oil cooler, changes from that if you have a remote filter, and chages again if you are using the two at the same time!!!!
Also the cam that comes in the crate motor is on a 110 separation with minimal lift and low duration, no torque above 4500 RPM!! Carb is most likely to large at higher RPMs with that cam. just my 2cents hope it helps!!

I was talking to my engine guy/installer. I told him about all the info here and he doesn't see how it can be the bypass. To quote him "GM is't stupid".......... I am getting frustrated. He is going to talk to his engine builder about it.
Anyhow, I lost the boat for the year, and about 20k into it. I WILL NOT have this issue next year. I think the boat is going to Active.... or at least the motor.

Thanks for the help.

RT

if the oil is foaming you have aeration in the pan due to windage. I don't believe the zz comes with a windage tray. Also if the engine has done this a few times you have possible damaged the bearings. I would pull the pan and pop off the front main and check the bearing. If the bearing has a "blotchy" look to it then you need to replace the bearing. The air bubbles have compromised the integrity of the babbit and this will lead to bearing failure.

Chris

Look here...
http://www.offshoreonly.com/forums/s...ght=gen+bypass

GM part number 25161284

Dave

Hopefully your engine builder has heard of the bypass problem. If not, he's not very well informed. GM does dumb things all the time. Look at the Aztek. ( I work there, I know. ) Do a search on oil bypass and see how many times this has been talked about.

Firewalker,
I can tell you right now that if the oil filter by-pass valve issue was not addressed that you need to ASAP! The other thing is that you can't use the oil filter/cooler adapter that was on the Gen IV motor. You need to run one that is for a Gen VI. I would suggest a billet one from Eddie Marine or Rex marine.
The ZZ502 cam isn't so bad but, I hope you used the right distributor gear, it should be a "melonized" gear specific by GM High Performance. Was the cam degreed before you put the motor in the boat? If you install that cam @ 110degree Intake lobe centerline you should see better top end. As far as running a cam with more lift I would check the specs on your valve springs if you are going to change cams.
You definetly should be running the 8quart Marine pan and I do agree that the bearings should be checked!
If you really want to wake up that motor, e-mail me & I will relay the gobs of experiences and ultimate success of over 550 reliable HP that I have with my 502!! It's the same basic motor but quite frankly you have a better set of heads to start with!!

The bypass valve is not the ENTIRE/ONLY issue. Just one chain in the link. Read the post by Arcticfriend. It will give you most all of the answers you are looking for. It is very informative and relates directly to your oil and oil temp issues.

Might also want to discuss this with more than one "engine guy/installer". He put a car engine in a boat. Lots of ZZ502's have been put to marine use successfully. Your guy failed to realize that a few simple changes are necessary. The changes are not that expensive. But they are necessary.

Also like cstraub said....windage tray!!

Good luck.

Firewalker, Lots of good infor here on this thread. Read them ALL. The oil bypass valve change is necessary. Think of the added restriction by adding the extra lines and remote oil filter unit. The oil pan MUST go. Aftermarket, Stef's, Teague, Hardin, etc. Please don't go the car aftermarket way. Some stuff crosses over, and some does NOT.

Really recommend you put on a recirculating pump. The only way to properly regulate the water temp (keeping it within a close tolerance of temps) and your motor will definitely like it. Of course after you have selected the right thermostat.
See pic of my ZZ502 project motors.
Three last words: Big Oil Cooler

All ZZ 502s come with factory windage trays. This is the same tray that is in all 500 HPs. Like Kidnova said the bypass valve is not the only issue, and I just want to say from having as many ZZ's pass through my shop I would say it is the least issue. This is a pressure diff valve and as the oil gets hotter the less the restriction through the filter.
The most important issue is oil amount and oil cooling which come from a bigger oil pan, cooler and having ample size lines with the correct adapters. If you look at his first post he said the oil dipstick had been spit out, and I'm sure the oil was too. This is more than likely why he lost oil pressure.
I would copy some of these posts and give them to your engine guy so you can have a trouble free NEXT summer and I would definitely take a look at the bottom end if you lost oil pressure under load at that kind of RPM.