Running hot. 1974 Mercruiser 166

[Don S]

Re: Running hot. 1974 Mercruiser 166

Lacquer thinner has no place on a boat, or on a car-It won't even remove finger- print oil.
Send it back-defective casting.
(use acetone)

Good Grief man don't go off the deep end over a can of lacquer thinner on his bench.

 

[ziggy]

Re: Running hot. 1974 Mercruiser 166

With no water you may have damaged the pump housing in the drive, the water pocket cover in the upper gear unit and the seals that seal the tube.
You may have also burned the hoses between the exhaust and the transom exhaust pipe and probably the exhaust shutters.

that souds like a typical overheat inspection.... surely a good idea....

 

[Coors]

Re: Running hot. 1974 Mercruiser 166

Good Grief man don't go off the deep end over a can of lacquer thinner on his bench.

Lol, Don; lacquer thinner is useless. not even a good hand cleaner,
use acetone or the real de-natured alcohol

 

[Coors]

Re: Running hot. 1974 Mercruiser 166

I started up the engine for the first time today on a hose. Felt the riser getting hot and then checked temp gauge. It was 195 degrees. Replaced the T-stat (which was already done this month) and restarted the engine. With the engine at idle temp is now at 160 degrees. It used run cooler on the hose at 140 or less. The riser is heating up too. Cant keep my hand on it for more than a couple seconds. Valve cover is cool after running for some time. What is causing this?
The boat is run in salt water. Osco riser is new. Osco manifold 3 yrs old. Entire water pump/impeller replaced over the winter. Also had the engine out of the boat last week to replace the exhaust elbow which contains the flappers. New flappers installed. Ran cool when winterizing last fall. The manifold water passages where the riser bolts up are clear. What do you guys think?

did it get hot/ was the impeller toasted? You may have pieces in there, restricting the water flow.

 

[CaptRon66]

Re: Running hot. 1974 Mercruiser 166

I change impellers every year. No pieces were ever found missing from them in the past. The new water pump was never run dry. Muffs and water was always on. However, without water running through the exhaust who knows about the things Don listed. I've done a water pocket before. The stainless screws in aluminum were not fun. I'll take Dons advice. It's easy to do now and will have peace of mind later. By the way . Lacquer thinner took about 10 minutes. Quicker than going to the store for acetone. I'm sure acetone is better though.
Ziggy, I just saw one of your posts. It's a brand new riser, definitely not plugged with rust from the manifold or block. Yes, I tried poking around with several different things. It's a casting problem.

 

[ziggy]

Re: Running hot. 1974 Mercruiser 166

It's a casting problem

hum, so where's it made? china? just out of courisity....

I've done a water pocket before. The stainless screws in aluminum were not fun.

ya, aint they a drag......

 

[CaptRon66]

Re: Running hot. 1974 Mercruiser 166

I just visited Osco's website. It says risers & manifolds are made in USA 100 percent. It was interesting to read that they had a marine engine line years back. I never heard anything good or bad about it....or of it.
There are a lot of guys around town here using Osco for years without issue. I've bought several and never had a problem before...but without working at a boatyard for years couldn't say what the failure rate is compared to OEM. A local marine mechanic told me they were good too.