Gen VI oil filter relief valves
 

need to make sure my gen VI oil pressure relif valves are correct...have a part # that came up on a search on here #25161284 just want to make sure if this is the correct one and are their 2 to change ? thanks Rob

Yes 25161284
Remove the one in the center, replace the one closest to the block.

My suggestion here is to replace the original oil relief valves with GM part number 25013759. This valve will allow more oil to be fed through your oil cooler before opening on differential pressure to stop to much bypassing back to pan. Stock valve has an approximate 11 psi max before it opens and the number above will see approximately 30 psi before it opens. I would recommend using a high volume heavy duty pump also like the Melling 10778 series pumps.

Best Regards,
Ray @ Raylar

Ray, On our gen 5 and gen 6 builds we replace 1 valve with the 11 lb stock and the other 1 with with the 30 lb. Are you saying replace them both with the 30 lb valves? I have found that leaving the center 1 out as 1BIGJIM suggests limits the oil getting to the upper end greatly reducing valve spring life.



Also Ray I will call tomorrow to order the throttle body and other items.

getting confusing ???

Brian,
I am not sure how leaving the center valve out would affect oiling in anything but a positive way. It can only be left out if you are not using the factory oil cooler passages in the block though. Leaving the center bypass out allows the oil to flow straight into the engine without having to make a couple of turns going through the GM block passages. That would help oil flow if anything, not hurt it and is the way I have always assembled them.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

+1. Do not use the passages on the block, plug them both. I remove the center relief valve completely and install the 30lb. valve on the filter pad. Use a billet remote adapter to connect the cooler lines, be sure to line up the supply passage in the adapter, the return goes to the center. Good Luck.

what are the differences between the #25161284 vs #25013759 ?

This thread now has me thinking about my set up.

I found this diagram and from what I remember when I took the engine apart and put it back together, the system looked like this...

http://www.marineengine.com/parts/me...ER+AND+ADAPTOR

Now where are the 11lb "valves" you are talking about?

They are not in the diagram you have, they are in the block where the filter adapter mounts. I think Ray got mixed up on the PN's, as the 25013759 is the 11lb, and the 25161284 is the 30lb bypass valve. As BillK said, the one in the middle valve. redirects the flow around some 90deg turns to get to the rear external cooler as used on trucks. Not used on most boats, so without the valve it is a straight shot into the engine.

Here is a link for verification. Notice in the description "For standard non-sanwich adapter applications use GM # 25013759."

http://paceperformance.com/i-5134579...oler-only.html

BillK is correct that the center plug needs to be removed if you want to have the oil to the cooler flow out and back only through the two taped holes on the pan rail in front of the oil filter pad location. In a Gen 5 or 6 block such as late model 502's and 496" (8.1L) these taped holes are there. On the Mercruiser engines Mercury uses a filter adapter plate which routes the oil out of the plate area out to the remote filter, through the cooler and back into one of these taped holes which is a return to the block oil system which requires the center valve to be in place. The relief valve is there so that if their is a pressure drop of more than the valve is set for it will open and allow the oil to go straight to the block oiling system and not starve the system for oil and obviously damage the engine. If the oil were to do this all the time it would not get properly cooled and filtered by the Mercruiser system. On the Mercruiser engine you have, if both pressure valves are in as they are on most stock blocks you should leave both valves in place and if you are replacing them, use the 25013759-30lb) valves for both. The pressure valves are not shown on the mercruiserparts.com diagram shown on this thread because they are in the block and not in the actual remote oil system shown in the diagram. As has been said previously, one is in the flat filter pad area in the block and one is in the deep threaded hole behind the threaded filter adapter fitting the Mercruiser filter adapter center bolt threads into.
Hope this helps clarify the confusion.

Best Regards,
Ray @ Raylar

Thanks Ray, that helps me out, engine oil system ran fine before the build, same stock valves were removed and replaced after build, according to machine shop. Nothing about the oil system was changed so I plan to leave well enough alone. I will monitor it first couple of times out and change if needed.......:coolcowboy:

do they pry out or are they threaded in ? sorry for all the questions..just trying to make sure I get this right before putting the engine in...yes 98 merc set up

Just screw a 3/8 bolt into the valve and pull it out. They come right out.

Ok, if running a std merc oil cooler and remote filter set-up which valve should I be using ? thanks...

Gen V & Gen VI Big Block Chevy Engines & All GM Performance Parts 454 & 502 crate engines use two of these bypass valves. Location for oil filter bypass valve is adjacent to oil filter nipple on oil filter mounting pad, Location for second valve (For oil cooler bypass) is above oil filter nipple in block on filter mounting pad. If a cooler is not connected to the oil cooler ports on the oil pan rail, the second valve is not needed. Engines using a sandwich adapter between the block and oil filter to connect a remote oil cooler must use GM # 25161284 oil filter bypass valve (in the location adjacent to oil filter nipple) to compensate for higher system backpressure.
The valve #25013759 is only a 11 psi diff
leave out the center one then the oil will go right to the main galley and not the bypass galley gm used for there air cooled cooler set up. and replace the other one witch is the oil filter bypass to a 25161284 oil filter bypass valve

I read a thread on here once that suggested to block off the pad bypass not in the threaded hole. I forget the details about why but if I can find the thread again I'll link it. What would be the thinking behind that?

You can install a 30 psi bypass valve or plug the outer pad
"oil filter bypass" not the center one that would be called the gm's oem air cooled cooler bypass valve the center is the many oil galley that feeds the engine.

Well said and I will add to that: Use #12 hose with the least restrictive fittings possible for your application.

So why wouldn't you just plug the outer pad bypass, stick a 30lb valve in the center and have done with it?

By the way, does anyone want a brand new teague remote pad filter / cooler adaptor for a mk4 BBC? I recieved a mk3 instead of a gen VI adaptor, oops!

I've always run mine plugged. That way, in case of a component failure, metal doesn't go all through your engine. Some people worry that if your filter get clogged, you don't get any oil flow but I've never seen much of a drop in oil pressure between oil changes.

You do not want the bypass valve in the center it is the main oil galley

Would anyone happen to have a photo of the center valve? I have a truck w/leaky oil cooler lines & I want to plug them the oil cooler lines for now.

Thank you.

Sorry to revive thread, I have a truck gen 6 454 and I'm about to stick it in my boat. I have a oil filter adapter bypass to run a bellhousing mounted oil cooler. I see all this back and forth talk about changing these valves.. I know there is a valve under filter and one next to it. The two holes next to filter area I plugged. Do I need to change valves and if so which valves?

Change the one on the oil filter pad area. If you don't, there is a good chance your motor won't last long. As long as both oil lines go to the filter adapter, the one (valve) in the center you can remove. It won't really hurt to leave it in, but it just give the oil a straight shot into the motor with doing a bunch of 90 degree turns to route the oil to the external ports that you plugged. This is the part you want to use.

http://paceperformance.com/i-5134579...oler-only.html

Give this thread a good read, I know it's long but it has some really good info. with pic's, of all your oiling questions, from fittings to lines, coolers and your bypass questions, this is the article that was given to me when I did my motor. Enjoy!


http://www.offshoreonly.com/forums/g...ardware-9.html

Well great. Have ran my motor for three hours so hopefully it's ok. My adapter has two fittings and they go straight through to the lines.looks different than the sandwich style. It's a Gen vi block. From what I gather there are two bypass valves on the motor where the filter would normally go. I need to leave the center one out and there's one which would be where the oil returns to the block and there's one on the side where the oil exits the block and goes to the cooler. It needs to be replaced with a 30lb. Is this correct. Thanks.

I'm not sure I even understand what I just wrote. From what I have read need to take bypass out of center on the block and bypass on side of block needs to be replaced with a 30 lb. My oil adapter has two lines. Exiting the bottom. One in center and one on outside. They are straight through holes.. Sounds like I might have my oil temp and sending unit in wrong place too. Its just plumbed in next to the adapter on the block.

Correct, the bypass is on the the filter pad once you remove the adapter. The center can be removed to avoid sending the oil around several 90deg turns, but is not absolutely necessary. The location of your sender sounds like it is in the right place. As far as temp, I'm not sure if that is before the cooler or after.