I shouldn't worry, should I?

[cheaperts]

1981 470, been running great, cooling great, just did alt conversion, all is well. Couple of evenings back I was out flinging teenagers off the tube, running pretty hard. Temp gauge (new this year, probe is in the exhaust manifold) never showed above 180-185. The old boat has idiot lights in the dash, I assumed they don't work, well low and behold I go to restart the boat after a tube run and the the temp light is glaring at me! Gauge was ok, 180, but the light was a glowing, then went off after 10-15 seconds. I'm guessing where ever the sender for the light is, climbs up some right after you shut down and then cools right off once it's running and flowing again. Only happened after short shut downs to swap out riders and went right out once the engine was running again. Not a problem, right? And what is the magic temp that should make me worry, 190? 200?

 

[stonyloam]

Re: I shouldn't worry, should I?

Maybe a little. If you have been running hard and shut off the engine the temperature of the coolant in the engine will clime some due to the residual heat. 180 (if the gauge is correct) is a little higher than I like to see even though normal operating temp range is 165-200. If you have a 3" exchanger and the impeller is more than 2 years old, it might be time for a new one.

 

[cr2k]

Re: I shouldn't worry, should I?

180 is high. You probably have a 160 thermo in the boat. Boats run way cooler then cars.

 

[cheaperts]

Re: I shouldn't worry, should I?

New impellor this spring before we ever ran her, I do need to change out the thermostat just because, and I haven't touched the water pump impellor on the engine itself. Not sure the gauge is absolutly accurate, I wonder what the factory light would be set for tempwise?
As I said above, goes out quickly once coolant is flowing again.

 

[stonyloam]

Re: I shouldn't worry, should I?

You might want to check the temperature, either with a IR thermometer or a radiator cap thermometer. You might also want to a take a look in the heat exchanger, there may be parts of the old impeller blocking some of the tubes, or it could just need a good cleaning. You can take the exchanger endcaps off without leaking antifreeze, only raw water under there. You should have a 165 degree thermostat in the engine. Your engine impeller, it is bolted to the end of the camshaft and should need no maintenance, the only thing that can go wrong with the engine pump is the cam seals can leak.

 

[guyaverage]

Re: I shouldn't worry, should I?

Everything you describe is pretty much how my 470 runs, and has pretty much forever. If I give it a hard run, then throttle back to idle (or shut it off) the temp quickly goes up 10-12 degrees or so, then within a minute or so of throttling back up or restarting the engine, the temps come right back down. I dont think you have anything to worry about at all.

Also I dont think 180 degrees isnt bad at all for a 470, if 180 is accurate. On a closed (pressurized) system like this, 180 isnt going to hurt anything. On an open system, then I'd be concerned. If it starts creeping up towards 195-200, then I'd start investigating. When I first got mine, I was running in the 190's all day long for most of the season. New impeller, acid cleaning the heat exchanger, and replacing the kinked hose from the transon to the heat exchanger dropped a good 15-20 degrees off that.

 

[cheaperts]

Re: I shouldn't worry, should I?

Yeah I think we're fine, it actually seems to me it takes a long time to get to temp, but we were really playing hard and a lot of 1/2 to WOT and off and back bursts abusing the tube riders just got it up there i think. I do like the thought of the Cap/temp gauge, can you get those at autozone or ? I was mainly amazed the 32 year old warning light hooked to spagetti under the dash still functioned!

 

[guyaverage]

Re: I shouldn't worry, should I?

My local Autozone didnt have them but Advance Auto did. It was like $30 or so. You can get a cheap I/R gun for that, and use it for checking other things too. I'd get the gun myself but the gauge in the cap has its own entertainment value.......

 

[stonyloam]

Re: I shouldn't worry, should I?

Yeah if it goes up to 180 and stabilizes at whatever speed you are running, then you are probably OK, if it creeps up under load or at idle then some investigation is warranted. As with any 470 (any motor for that matter) KEEP AN EYE ON THE TEMP GAUGE. In the meantime have fun!

 

[cheaperts]

Re: I shouldn't worry, should I?

Had her out today, found that running on and off, idling we showed 170-180 on the gauge, got a Mr Gasket thermo cap as a back up indicator, seems to show 5-10 degress higher than the gauge. When we decided to head down lake to the party island and ran steady for 5minutes the gauge went to 190, Mr gasket showed 200 As soon as we go to idle it would quickly come back down, so next we will replace thermostat and open up the heat exchanger (3" dang it) and clean it out real well, maybe even have it cleaned by the radiator shop. Do you have to replace gaskets on the ends of the exchanger when you open it or is it a rubber seal? And is the thermostat 160 or 165? I've seen both referenced

 

[stonyloam]

Re: I shouldn't worry, should I?

It would be wise to replace the gaskets, 165 according to the manual

 

[cheaperts]

Re: I shouldn't worry, should I?

ok, took the heat exchanger off, opened it up, found a piece of debris in the first chamber where the raw water comes in, not big but enough to cover 3 or 4 tubes, also found the inlet for the raw water to be about 1/3 flattened, that might have a bigger impact. But the part I can't figure out is that the closed/coolant part of the exchanger, has SAND packed around the tubes on one end, how in the %&*% could you get SAND in the closed side of the system. I very carefully got some out and it definately appears to be sand, gonna ttry to flush and flush and flush and get it all out of there. I think I can carefully reround the inlet pipe on the sea water side. Other than the sand, it appears to be pretty .
Thermostat...... is there a museum I can send it to? Will be replaced immeadiately.

 

[BonairII]

Re: I shouldn't worry, should I?

Thermostat...... is there a museum I can send it to?

It always amazes me that people(in general) wait for a t-stat to fail before replacing them. IMO they should be inspected every season....and replaced regularly(whether they look good or not).