Donman

489 cubic inches, 500+ hp. Still running stock Merc oil cooler. Oil temp sender in bottom of pan. Seeing 260 degrees at WOT. 230* at cruise rpm.
What size oil cooler would you recommend? Where is best place to buy from? What kind of money should I expect to spend?

TC

I am having the same problem. I built a 496 and have also surpassed the cooling ability of my stock 454 mag oil cooler. I thought it might be an issue with the added HP but I just hoped for the best. Not sure of my temps but my oil pressure stays at 60psi as long as I keep the rpm below 4000. A 5500rpm run will cause the pressure to drop to 40psi and will go right to 60psi after a short low rpm cool down. Will be looking forward to readers input.

vandeano

The information I received from my earlier post is that your oil temp is fine. Don't fix what ain't broke.

RLW

Higher Power,
Your temps seem fine. 260* Pan at WOT
But, is temp sender matched to gauge?

TC,
Need to know your temps before you can make an educated assessment of your needs.
A 5500rpm run will cause the pressure to drop to 40psi and will go right to 60psi after a short low rpm cool down.
Is that 40lbs. at idle or 5500 RPM?
If those are idle pressures, they look good to me.
General Rule of Thumb is 10 lbs oil pressure for every 1000 RPM.

Put an oil temp gauge in that boat. Make sure sender is matched to the gauge.

Donman

My gauges are Gaffrig, the sender was purchased at same time as gauge, from same source. The sender came in a Gaffrig box, so I`m assuming they are a match.
My concern is once temp hits 260 at WOT, it stays there for a while, even after backing off throttle.
I would just prefer the oil temp to be a tad lower.
I`ve heard "acceptable" oil temps all over the scale, from 230-280 and even 300 if not there long.

Can somebody please elaborate more on the subject of oil temps ???

teaguecustommarine

you should be reading your oil temp after the cooler.
we like to put the sender in the oil filter assy before it
goes back into the motor.
what cooler are you running? mercury make a
few different sizes and the HP500 is using the 3"dia
cooler, you should at least be running that but i
would try relocating your sender first before spending
the money on another cooler that you may not need

RLW

Teague,
Your post indicates that you are filtering oil after the oil cooler.
Am I reading that correctly?
Filtering after the cooler is new to me.

The HP500/502 Carb oil cooler is 2" x 17". Not to say they didn't change along the way. The HP500/540 Bulldog used a 2" x 21".
Maybe the HP500EFI uses the 3" oil cooler.

teaguecustommarine

the cooler from the HP500 would be a part # 849952T01
and we do filter the oil after the cooler or better yet
we filter all the oil before it goes back into the engine

MESABALANCING

I've never seen a Merc 3 inch cooler I use only 3 inch coolers in my marine packages CP and TCM offer them the way I run then is after the filter and I also install the sending unit on the filter adapter but I want to know the temp of the oil as it comes out of the engine not after the cooler I feel thats more important to me . I've had this same problem with other engines and a simple fix has been changing to synthetic has brought the temp down as much as 30-40 degrees you dont want to make the oil any cooler then 220 wide open thats optimum operating temp for any oil . Good Luck Laz Mesa www.mesabalancing.com

RLW

Teague,
Thanks for the information and oil schematic.
Eickert also filters after the cooler. That's two identical responses from the pros worth implementing.

Just for clarification.
Part # 849952T01 is for HP500EFI

1994-95 HP500
816074T 17.50"
848192T 21.75"

1996-98 HP500
848192T

Do you guys run any thermostatic controlling devices in your oil systems?
Thanks again!