I am working on my '87 Formula F311 SR1 this winter. Just bought the boat last year, and it needed some TLC. It has 454/420's in it with B&M 174 blowers with around 400 hrs. BW tranny's and TRS drives. TB IV ignition at 28 degrees. I run it offshore in New England. After much general maintaince to get her seaworthy, I ended the season with 2 major problems as I saw it:

- One engine overheats with a thermostat in - take it out and everything is fine, except no engine temp (not the thermostat I swapped it for a known good one)

- The other engine is getting some water in the oil (aka milkshake) It seems to do it more when hitting high speeds. It also leaks / drips a small amount of oil toward the rear of the engine - couldn't pinpoint it with the motor in the boat.

The intakes were fairly rotted (maybe the source of the leak?), and I have new ones in hand as well as the thermostat extenders.

The blowers are at the Blower Shop now and are about to be rebuilt (slightly noisy and didn't want to take a chance). I had Nickerson performance rebuild / update the carbs last summer. Exhaust is EMI and is 2 years old. I put Stainless Marine bypasses on last summer, as the circulator pumps were leaking. Many other new smaller parts as well (water pumps, etc).

The engines are coming out next week so we can better inspect their condition. With the exception of the problems listed above the boat runs great. What I am trying to decide is how much work is worth putting into these engines, or should just looking for crate motors and starting over? I am trying not to break the bank, but don't want to break down during our next short New England summer.

I know there is a lot of expertise on this forum, and would appreciate any insight / opinions on this project.

Fix 'em, replace 'em, or do the minimum and just run it?
Thanks!

If one engine is getting water in the oil you definitly have to fix it.

If you're lucky it is a blown headgasket.
Less lucky,cracked block/head.

The oil leak is probably the rear main bearing oil seal.

If you're happy with your engines,do a comlete rebuild.

It's possible that the water pressure is a bit high, and that it's pushing some water past the intake gasket(s), especially with some water passage corrosion.
38KV is probably correct about the oil leak but it doesn't hurt to double-check the oil pressure senders at the back of the block. You might have one down by the oil filter adaptor too.
On the temp issue, are the two engines identical as far as plumbing and thermostat housings are concerned?

Hi Crazyhorse,

That would be nice if it is just a water pressure issue. I have seen posts about that issue. Does anyone have a link to a pressure gauge suitable for testing this? I have transom mounted water pickup going through 1 1/4" hose through sea strainers then up to the pumps. I think I am going to pull the heads off of that engine and have them checked anyways, possibly install new valve springs. Where water (salt) was getting in, do I need to disassemble the lower end too?

On the temp engine problem, both engines are plumbed identically. One strange thing to note is that the raw water pump drips through the hole in the bottom. I replaced it with a used one, and then a new one too. All 3 of them dripped for some reason, even when the engine is off. The only other thing that I can think of is that I have the sea strainers tapped for fresh water flushing. When I connect the flush system on that motor to the hose, water is leaking out past the sea strainer gaskets in a good amount. It doesn't leak when running normal. Maybe it is sucking in air, and it is getting trapped at the thermostat?

The sea strainers can and will let air in if the top isn't tight or if the gasket is bad. That's a common overtemp problem on inboard cruisers. Go-fast boats typically run fast enough to force water through the sea strainer when on plane but if it's a bad enough leak at the gasket it can still pull air.
Chances are, though, that you've got another issue, possibly a head gasket that's passing combustion gasses into the water jacket.

Crazy is on track.

If it overheats with a tstat, and does the same if you swap tstats.

AND

you got milkshake.

I'd look awful hard at headgaskets.

Actually, it is 2 separate motors, 1 having the milkshake, one having the overheat.

One other thing on the milkshake - the oil level isn't really rising, just that when I pull the stick, it's there. Also can see it inside the valve covers when looking into the oil fill hole.

I am also wondering considering the age of the motors (original 1987's 454 / 420's) and that they have had the superchargers installed for about 10 years, how much $$ is really worth putting into them? They perform great, but could I get a short / long block somewhere for a reasonable cost (if so, any suggestions greatly appreciated)? Or just start tearing these down until any / all suspect and recommended maintenance parts are replaced?

I'm just not sure what is the best approach.

you running circ pumps?

I am running a corssover aon avery similar engien and had temp issue until i pulle dout the thermostat. SH etake as while to heat up now so it has to idle at the dock for a while but once it warms up its fine.

geta water psi guage maybe you have too much and thats whats causing water in the oil.

No circ pumps, crossovers. I put thermostats in the motors to see if the milkshake was just condensation, and the circ pumps leaked like crazy. So I just decided to go for crossovers, especially using the superchargers -figured the extra cooling would be better.

The funny thing is that the motor that has the milkshake runs fine with the thermostat. The other one that has no apparent problems can't run a thermostat without overheating. Both motors are set up identical. Go figure?

If you have the original engines from 1987 and the circ pumps leaked like crazy,I think there is a chance the water passages in the block/heads is choked up with rust.

I had that problem with my previous boat (also from 1987).
The engine overheated and when I teared it down,It was so corroded it went straight to the junkyard.

If that is the case, it wouldn't be a bad idea to look for new longblocks.