Help with possible overheating issue?

SR_PACHANGA22

New Member
Apr 19, 2007
11
I have a 87 SR pachanga 22 with 454Magnum 330hp and last fall when I went to winterize the boat I found that there was no thermostat installed. I took it all apart and reinstalled the tstat 140 degrees new upper and lower gaskets and the cork gasket between the tstat and spacer. Ran it on the earmuffs after to check for leaks and the temp gauge climbed to close to 170 at idle around 800rpm. I shut it down rechecked for leaks made sure the ear muffs didnt come off the drive and restarted it after a few more minutes the needle went down to about 125-130 ish --so i assumed at that point the tstat opened up but after maybe another 4-5 min the temp gauge was reading close to 170 again. I felt the risers they were not hot at all warm but not HOT I could feel the water going to the manfolds through the hoses and also to the risers even touching the t stat housing it was much warmer then risers but not where I could not keep my hand on it... I am wondering if its a bad tsat? possibly bad sending unit or maybe water pump impeller gone bad? Other odd thing when I turned on the Nav lights ALL of my gauge needles jumped(decreased in value momentarily) a little in value like oil pressure water temp and the volts each time i turned the Nav light switch on/off it caused the same issue--thinking maybe bad ground causing that ? but its the temp issue that concerns me most.... all season last year the temp gauge NEVER got near 170 --without a tstat im sure i know why but what do you think the "normal" range should be ?Not sure if it matters or is an area of concern but the boat has the big through hull exhaust at the outside corners of the transom and the boat ALWAYS has steam coming out with the exhaust even when running on the ear muffs. Plugs all come out looking normal no buildup no chalking or corrosion and it has plenty of power/no missfires and last summer I replaced the exhaust manifolds and risers --the ones that came off were not the worst I have ever seen but not pretty either the boat USED to be in brackish water --Judson river around stony's point NY originally but last 2 years has been fresh water . Any help / suggestions would be greatly appreciated
 
You haven't said whether your boat is raw water cooled, or a closed cooling system.
I believe that the max operating temp on raw water cooled boats is 160 or so. I've been told that salt (in salt water) crystalizes at warmer operating temps, but I don't know for sure.
Are you sure that the temp gauge is correct?
 
170 degrees does not sound like it is out of line. I would first give it a lake test to see what happens and if it remains there then it's probably OK.

But you just have to wonder why there was no t-stat in there to begin with.
 
Let's not get the cart before the horse..........

A Merc 454 needs a lot of water flow to cool it. You could just be running out of water with the hose. I wouldn't do anything until I ran the boat in the water to see if the regular water flow made the temps more regular.

I had a pair of 454's in an inboard and with no obstruction like a lower unit and small dia piping a 5/8" hose with 45 psi of pressure would not flow enough to cool the engines. I'd have to shut them down when the temp gauge began to rise.
 
correct me if I'm wrong but are t-stats to assure minimum water temp so the engine reaches optimum operating temp quicker?

Different t-stats have different temps, so in this case 140 degree tstat will open when the temp reaches 140 and then get water from the lake (or radiator in closed cooled). Should really effect the max temp.

That said, I'm wondering if the tstat is obstructing the amount of water that can pass through the cooling system thereby increasing your operating temp.
 
Sorry I left out that detail it is raw water cooled not closed. I will be hopefully getting it in the water on sat or sunday FINALLY supposed to be mid sixties here though I am sure the water temp in the river will be mid 50's or so. I am NOT sure that the gauge or the sender even might be bad or could be nothign at all. Possible could be the impeller vanes have dry rotted and broken I haven't yet replaced it yet and who knows when the last time it was done( I know I probably should just do it know and getit over with and then at least i KNOW when it was done) I just want to make sure that there is not somethign else I might be overlooking too and I apreciate the wisdom -advise- and experience of those skippers who are more seasoned then I . -- I bought the boat last year but it really didn't come with any service records. Overall the boat only has about 220 hours on it --not horrible for an 87 but still it was used in brackish water for several (at least) of those years. Ill report back again after I get it in the water. Was just looking for some suggestions.
Thanks for all the help!
chris
 
SR_PACHANGA22 said:
Possible could be the impeller vanes have dry rotted and broken I haven't yet replaced it yet and who knows when the last time it was done( I know I probably should just do it know and getit over with and then at least i KNOW when it was done) Ill report back again after I get it in the water. Was just looking for some suggestions.
Thanks for all the help!
chris

I would bet money that you hit the nail on the head. :smt038
 
Just save yourself some time and go ahead and replace the impellor..........fishing broken impellor blades out of a cooling system is a pain in the ---.
 
OK So GORGEOUS day finally here I get the boat in the water and temp gauge reads about 1/2 between the 140/170 mark so im gonna call it like 155/160ish. It doen't take long at all to get up to temperature cruising around 3000-3500 rpm running I would call it about 160/165 @ WOT ~4400 rpm gauge is showing 170 also runs up to 170 when you come off plane like for no wake zone. Judging by last summer it always stayed around the 140/150 mark but was with NO tstat at all. So now I guess I have more work ahead. I suppose it could be bad t stat also.. prolly should have checked but I assumed since it was brand new .. :smt021 .sighs I guess I'll yank the drive off tomorrow and start with the impellor I need to lube the splines check u joints and all that anyway. Question is --- does this seem too hot for it to be NORMAL? I cant seeme to find in the manual anywhere where it states correct temp.

Thanks
 
fwebster said:
Just save yourself some time and go ahead and replace the impellor..........fishing broken impellor blades out of a cooling system is a pain in the ---.
Seems to me you should have done this first, then tried it. But having said that, 170 is normal for my boat. I would worry if it did not get to at least 160. Actually, I would fix it.
 
From your posts, I'd say you need to go ahead and replace the impellors, butr on the temperature, I'm not for fixing stuff that ain't broke. As I recall, our sea water cooled 454's ran in the 160-165 degree area and they did fine, but tended to run rich. Closed cooled 454's typically run in the 175-180 degree area..........so I"m having a problem understanding what needs fixing.

ANd, don't trust your gauges to be any better than to within 5-10 degrees of right. If you are disturbed about that much difference, run the boat a while and see what happens after you change impellors. The important thing is to not let the engines run hot. If you see temps over about 200 degrees, slow down and figure out what's going on.
 
I cannot seem to find what is the "normal" operating temp range. That was my initial question. Since it ran around 140-150 all last year (mind you it did not have a tstat in last summer) and after installing the 140 tstat its now running up to the 170 mark I just wanted to know what is the correct range? obviously over 200 is a problem but I was just looking to have an idea of what "normal" is.


again thanks for the responses.
 
Thanks for the replies I guess I found what I was looking for that "normal range would be 160-170. The owners manual tells you to "operate within the normal operating range" and just shows this attached picture. Now you can understand why I was unsure. No where in the book does it give u the range in degrees just this useless picture...which of course is not even a picture of the gauge that is in the boat!

Again thanks for all your responses.
 

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