HP350SC

HELP!!!Was getting ready to purchase a t-stat oil cooler, but notice the Merc. oil filter adapter shows one internally? My oil temps are too low(<170 cruising, 200 deg. after long WOT pass) and I'm getting excessive condensation in motor. It is a '97 HP500 with 3.3 Whipple, no cooling system t-stat, just 5/8 restrictor disc. and crossover. Rear of intake tapped to bleed off water. Oil pressure 60 lbs. max.,35 at idle. Head gaskets good, and no mechanical issues with motor.
I boat in the NW, usually cold water temps and 70-80 deg. ambient.
Engine also runs very cold, usually will barely register on gauge, and yes it works.
Should I bring cooling system temps up, thereby raising oil temp? I could plumb the stock check balls and tee back in.
Or should I just address oil temp? Shouldn't the Merc. oil t-stat be working? I have disassembled the oil filter adapter and I'm going to test the t-stat plunger.......

RLW

I would try some thermostats first. 142 and 160. It definitely helped me during the late season runs. I run a crossover with bypass, and 160 T-stat has three holes in it. Holes are .155"
Do you have milk under the valve covers?

HP350SC

Yes, pretty milkshaked. I have a bung on top of crossover, I could put the Merc. tee w/check balls on, and a thermostat in the housing.

RLW

Crossovers can be a pain. I have been through the ups and downs.
Dean Nickerson clued me in on my current setup and it is successful. My crossover is a Stainless Marine. I usually run a 142 T-stat with (3) .188" holes, for the warmer months. I do use a Mercury Racing Oil T-Stat filter mount, also.

TC

RLW, If you have a bypass what is the purpose of the 3 holes in the thermostat?

HP350SC

I would say to keep steam pockets from forming. My motor tilts back a ways, I will probably do a 3/16" hole at top of t-stat.

RLW

Yes, the (3) holes help keep some flow of water through the block so steam pockets do not form. That is what I have been told.
The bypass maintains a supply of water flowing to the exhaust manifolds.

HP350C,
I do not know what one 3/16" hole is going to do for you. Try it and let us know how you make out.

TC

That makes sense.

HP350SC

Took apart my oil filter adapter and tested oil t-stat, no worky at all at 210 deg. Will replace that and report back. I don't think it has worked since I bought the boat, and I did not know there was a t-stat in there.

ratman

i thought the holes in the t stat were to keep some water flowing thru the exhaust to keep it from getting too hot while the engine has the t stat closed.