1986 Mercruiser 305 optimum temperature

[TheHunter990]

We have been noticing some white greasy sludge on the valve cover caps, and in the 2 breather hoses to the carbs (one was completely plugged with it).

Our engine is runing at 150 F on the top of the thermostat housing, does that seem right? (Checked with a infrared gun).
The engine oil is looks very clean, no hint of water in oil, and it also doesn't burn much oil. We are just concerned about the amount of white sludge in the top end, which could be explained if 150F is to cold.

I have a some questions.
1. Why don't merc's have a PCV system like all autos do?
2. What are the hoses running up to the flame arrestor supposed to accomplish?
3. Would there be any harm in switching over to a PCV system?
4. What is the correct temp?

Thanks

 

[Don S]

Re: 1986 Mercruiser 305 optimum temperature

1. Why don't merc's have a PCV system like all autos do?

They didn't see a need for it.

2. What are the hoses running up to the flame arrestor supposed to accomplish?

They pull the fumes from the engine and send it out the exhaust.

3. Would there be any harm in switching over to a PCV system?

No need to, see item 2

4. What is the correct temp?

You have a 143? thermostat in it, that means it starts opening at 143, so your 150 sounds about right.

 

[TheHunter990]

Re: 1986 Mercruiser 305 optimum temperature

Any ideas on whats cause the white sludge build up? Is it normal, don't worry about it?

 

[spdracr39]

Re: 1986 Mercruiser 305 optimum temperature

Pictures ? Could just be normal condensation if the engine doesn't get run often or is operated at short intervals and shut down all the time before reaching full operating temp.

 

[TheHunter990]

Re: 1986 Mercruiser 305 optimum temperature

This is what both valve cover caps look like, and the breather hose was plugged this the same stuff.
We run the boat 2-3 hours at a time.

I pulled a valve cover cap when the engine was running once, and steam was coming out pretty good.