Overheating at high Rpms help!& rust and lime dissolver???

[sebas54]

I have a 1987 4.3l gm v6 alpha 1. It has been over heating for some time now. I just replaced the impeller, impeller housing, and the entire gimbal kit, in hoping it would fix it but it didn't. I have removed all the house and tested them for obstruction and there wasn't any.

I am going to change the water circulating pump. I think it makes a buzzing sound so hopefully that will solve it.


Has anyone ever used the rust and lime dissolver that you use on your house, on your boat? I was thinking that if it has an obstruction due to rust then maybe that the pipe cleaner would work.

 

[Don S]

Re: Overheating at high Rpms help!& rust and lime dissolver???

Time to pull the risers and inspect for plugs in the water passages. Both from the manifold passages and the riser passages.
IF they are plugged up, time to replace all. They are giving you a warning. the next step if they are plugged up is to corrode through and likely destroy your engine.

 

[sebas54]

Re: Overheating at high Rpms help!& rust and lime dissolver???

The risers and exhaust manifold are only 2 seasons old. Is that how long they usaully last?

 

[Don S]

Re: Overheating at high Rpms help!& rust and lime dissolver???

The risers and exhaust manifold are only 2 seasons old. Is that how long they usaully last?

No, they last longer than that, but I had no way of knowing what previous maintenance was done on it. Manifolds and risers are probably the most common reason for high rpm overheats.

 

[Lodgepole]

Re: Overheating at high Rpms help!& rust and lime dissolver???

If your set up has flapper valves, a valve rotted off can catch in the drive port and cause overheating. I had this problem on my 92 OMC.

 

[sebas54]

Re: Overheating at high Rpms help!& rust and lime dissolver???

Hw do you check if the flapper is drive port. I just had the outdrive off and changed the gimbal bearings and all the bellows.

Also I just checked the risers and all was good.

 

[cr2k]

Re: Overheating at high Rpms help!& rust and lime dissolver???

With the drive off you can look in to the exhaust port and maybe see if the flapper is in there. Other way is to check to see if it is still in the top of the exhaust pipe just below the rubber coupler from the riser/elbow.

 

[proxyx]

Re: Overheating at high Rpms help!& rust and lime dissolver???

rust and lime dissolver - muriatic acid (~20% hydrochloric acid) or sulphuric acid (better)- fast drain unclogger ("liquid lightning") 50-80% acid - hardware store
http://www.liquidlightning.net/template.php?go=home
or equivalent
2 years for manifolds - risers even in salt water way too little - 5/6 years is more like it and that is minimum... and yes I used it, depending on the condition 1-3 fill-ups (off the boat, LOL) with about 10-15% acid solution and screwdriver makes them like new, rinse
check spark plugs for water, engine timing (too advanced) and if idle mix is not too lean
if you suspect circulating pump (noise) replace it

 

[jtybt]

Re: Overheating at high Rpms help!& rust and lime dissolver???

What are your symptoms? Do you have one piece manifolds/risers or two piece. Raw water cooled? Do you boat in salt water?

Check condition of thermostat housing for rust scale build-up. Also, you can pop out a freeze plug to see what condition the water jacket looks like as far as rust build-up.