Water Test ends with overheating!

First off I have read every post about idles, and overheating issues.. this one is a mixture of all... I hope someone can help.

I have this senario:

This is the second water test on my newly purchased 1977 ski nautique.. engine ford 351 - holley carb.

So, I start it up and it warms up to 180 degrees within only 10 minutes of idle and a few minutes of running in nice clean cold water...

The Facts:

At 180 it hates to be shut off. And runs rough over 170... It loves 150 to 160!

The PO had the idle set at aprox 900 to 1000 rpms - seems very high.

I have been through the entire water coolant system - check impeller blades, intake hoses and trans pump - all working looking good. I have tightened all hose clamps hard. No Leaks are sighted... yet - here is something to consider regarding the coolant system.

From the intake to the Trans coolant filter pump the hose is not standard water intake... it is a retro fit hard orange hose then it goes from several fittings and other spliced houses to the impeller pump, which I have taken apart and is in good working order... The impeller is new, yet the pump looks old.


Also, the PO mentioned the belt drive that goes onto the RWP is from an unknown source and of unknown origin... could it be the belt is not turning fast enough?

COULD IT BE : I need a new RWP?

I need new hoses? They dont leak?

I need just a basic tune up?

Allot to consider I know.

BTW - My shifter and trans issues are NOW resolve due to the folks here on this forum!!!!

Thanks Guys.
Jamie

newbie

Have you tried the bucket test for the RWP? That would eliminate your question about the pump, belt, and half the hoses.

Do a search for "Bucket test" and you should find the details. There are two ways to do it, you can suck out of the bucket or fill it up. Either way should take about 20 seconds or less for 5 gallons, if I remember correctly.

I wonder how long it was run without the strainer; is there a cup strainer inline? If not you could have pieces of whatever lodged in somewhere. You probably checked, but the oil cooler will trap debris.

I had the same orange hose on my 79 but it didn't have any splices. It went straight to the cooler(around the tranny once).

I have searched the forum and cant find a visual - picture of a 5 gal bucket test.

I put a piece of a garden hose in a bucket - primed the water pump and hoses first... then put the hose inside another hose which ran to the RWP - the water hose diameter is smaller than the other intake hoses.

I started up the boat then inspected the water in the bucket.... It was now going down remotely fast in aprox 34 to 40 seconds it had only drained the bucket down a few inches with LOTS more to go, I felt the hose and it was very slight suchion....

could it be my set up is too restricting?

So, that said: Can someone send me some details on how to rule our your RWP?

Cheers... Learning ALLOt.
jamie

need more beer...

Jamie, You have mentioned "splices" in hoses. I think it may be time to replace the hoses back to original and then start over with trouble shooting. You state that they "don't leak" but they may be sucking air.

Greg (buffalo) mentioned a strainer. He is reffering to a inline basket type that was used on later year boats. I feel to are referring to the one on the bottom of the boat - correct? There isn't a tranmission strainer. You may be looking at the trans cooler.

wakesurfer wrote: my boat needs a strainer... I will try it. No strainer equals no good!

Why?? None of my boats have ever had strainers. Never had a issue but of coarse I don't boat in swamps ether!

Jamie, lots of good advice on here already.
I suggest you perform a basic tune up which includes setting the timing properly with a timing light. Then adjust your idle if it is still high.
As for the overheating: After replacing the splices go ahead and replace the thermostat with one that is recommended for your applications. Probably a 160 degree t-stat. the stat that is in there is probably of a higher operating temperature- too hot.

Good luck and be sure to report back with your progress so this can be used as a reference for others.

-Brad

I found the t stat, and it is a rusty one... and I am sure the original of over 1,000hrs.

just wondering which one to buy?

skidim has several for the PCM 351 engine.

Any ideas?

Thanks gents.,
jamie

Barracuda wrote: After replacing the splices go ahead and replace the thermostat with one that is recommended for your applications. Probably a 160 degree t-stat. the stat that is in there is probably of a higher operating temperature- too hot.

A 160 'stat will cause the same problem (and have him running at 180+). He needs a 142, which would keep the temp at 160.

Jamie,
Somethings not correct or I'm very confused! You have 1&1/4" ID hose somehow "spliced" to a trans cooler that has hose barbs (the male ends for the hose) made for 1" ID hose?? Post some pictures of these "splices" or try describing them again. Off hand, it sounds like potential spots to suck air.

I assume my coolant system should be intake to trans cooler to RWP.

Its just my ID's of my system are not the same.

wakesurfer wrote: Exactly! My intake through hull ID is 1and1/4 ------ that hose is connected to the trans cooler ID 1inch. I have a hoses coupling reducer for the 4 inches of hose that come off the trans cooler. I think I am just going to get a single piece of 1 and 1/4 and make it really tight on the 1 inch ID connections. Any tips or similar set ups? Is this common? LAST GREAT COMMENT! I was told by several marine mechanics to not even use a thermostat! Any thoughts on running w out a s tat! I am such a rookie.

Jamie, It sure sounds like a PO replaced the trans cooler with a 1" instead of the correct 1&1/4". This is putting a restriction on water flow and with the reducer couplings/connections it adds to the number of points that are potential leaks. When you ran the bucket test, you pulled the 1&1/4" off the RWP and put it in the bucket. This bypassed the problem area with the restrictions and the potential leaks (air). This should be the correct cooler: trans cooler
I suggest you get the new cooler. Your idea of trying to clamp a 1&1/4" hose on the 1" barb on the cooler won't work. You will never get it clamped down that far.

Running without a T stat is not a good idea. There is a complete thread on it that just popped up again. I'm sorry to here that you have heard from marine "mechanics" to run without one. If they said that, I personally wouldn't take a lawnmower to any of them!! At least you didn't refer to them as "technicians"!!!
"running without thermostats"

Well here is the latest... It appears to be a combination of several things: Old cracked intake hoses reducing down to a 1 inch trans cooler then onto a old 160 t stat. I replaced the hoses and removed the t stat.

Got a 142 in the mail from Skidim. Still not sold on the reason why to use a t stat in an older 351 engine that needs all the water it can get to stay cool... in my case I have a smaller diameter trans cooler.

How many folks out there run w out t stats?

Did a dry garage test and it ran good.

Thanks again for all the wonderful input!!!

Off to lake test for the finally!   God Speed.

Thanks for the insight.

What should a 351 commander engine temp be during normal operation?

Mine goes from 140 to 160 w out a t stat and 180 to 190 w 160 t stat.

What is the difference of the commander engine to others.. do they like it hot?

No worries... I have a 142 t stat in the mail.

Pete,
Just wondering, why do some people refer to a 142 degree t-stat and others refer to a 143. Are these the same thing?