Mercruiser Temp Question

[othelloears]

I have a 1984 mercruiser 228 that seems to be running slightly hotter this year.

At idle and slow I am about 145 degrees and cruising at @ 3k I run at 150 degrees.

It used to stay on 145 no matter what. Assuming I have some build up in risers/manifolds.

I would like to know what temp (at gauge) is an acceptable range.

Thanks

 

[Stamey]

Re: Mercruiser Temp Question

Normal temp on my 1983 305 is 160.

Chris

 

[Daleg70]

Re: Mercruiser Temp Question

you are looking at a small difference which may or may not even be reaL. Put your hands (carefully) on the risers. Is there a big difference between them? == are they so hot you can barely touch them? If they are extremely hot and been there a while it may be they are a the end of their life. Plugged manifolds/risers restrict the water flow and lead to overheating ----perhaps even/just the water pump impeller

- your temperature change sounds so small I would not do much unless there is some other indicator.

I did have a boat with a log manifold 228 for about 20 years (same engine) -- eventually changed it over to center riser as the parts are cheaper and it is not that difficult if you have to replace it all anyway.

 

[Daleg70]

Re: Mercruiser Temp Question

by the way --- the salt eventually got to my 228 (after 20 years in fresh water and five in salt) and I replaced the 305 with a 350 --- everything is a direct bolt in --- my old MR drive still handled it, your is probably slightly newer drive --- the extra HP was great -- regretted I did not do it years earlier.
pretty easy change.

 

[Don S]

Re: Mercruiser Temp Question

If you normally run at 145, and it suddenly goes up to 150, something has changed. When was the last time the impeller was replaced?

 

[othelloears]

Re: Mercruiser Temp Question

Thanks for all the responses. I didn't think it was a big deal but wanted to know what everyone else was looking at.

This is my 4th season in the boat and I don't know how old the man/risers are so I assume they will need replacement. I plan to pull them after this season and either soak in acid or replace depending on what I find. Don't want to pull them know and break a bolt. PBS has the whole OEM ceramic ciated kit for 900$

I know the engine is also nearing the end. Its an 1984 but only has 950 hours. i had to pull the engine last year to do the coupler and alomost pulled the trigger. I plan to run it to the end and replace. I am considering the 350 but am concerned about fuel consumption. Did you notice a big jump? I found short block rebuilts online for 1450$

I cruise at 3000 rpms at about 27 MPH. Seems good to me. Gas is bad enough already. i heard the 350/260's were pigs

 

[wca_tim]

Re: Mercruiser Temp Question

how about the impeller? that's the most likely first place to start for a slight loss in cooling or increase in temp...

 

[othelloears]

Re: Mercruiser Temp Question

Just replaced it. It was overheating (180-200) at high speeds. Looks like the man/risers are clogging up.

 

[othelloears]

Re: Mercruiser Temp Question

Been running the boat for a couple weeks and gets hotter and hotter each time. Now runs up to 200after 5 mins of cruising. Just ordered the OEM risers and manifolds from PBS.

Does anyone know the torque specs for the manifolds and risers. My book says 25 lbs which seems way to light.