Running hot again...

[burgettw]

I finally got a chance to take my boat out 5.7 chevy omc cobra outdrive and ran good all day till battery starting getting weak so while sitting at dock at idle for about 5-7 mins maybe to go get another battery when I got back it was like 210 I thought I had overheating problem done but I am running out of ideas to do I have changed every water item on my boat and it runs about 180 or 190 everyone is telling me it should not run more than 160 why is this or what is is supposed to run?

Thanks for yall help

[VetteLT193]

I think cutwater went through this about a year ago... might want to search.

What did you change?
What Thermostat do you have installed?
What does the water flow look like (Cutwater has his Minx on youtube that shows the water flow so you can compare)

An easy check to see if the T-stat is the issue is to just pull it out and see how it runs without one.

[burgettw]

I think cutwater went through this about a year ago... might want to search.

What did you change?
What Thermostat do you have installed?
What does the water flow look like (Cutwater has his Minx on youtube that shows the water flow so you can compare)

An easy check to see if the T-stat is the issue is to just pull it out and see how it runs without one.

Yes sir I took it and ran it without the t-stat and not much change at all

I have a 140 installed...water flow looks good I ran it when we got home on the hose and it ran fine.

I changed the front water pump, impeller, all hoses, t-stat neck, and new guage...is there anything else I need to change? and why only at idle?
does the tilt/trim have anything to do with it because outdrive was up alot real shallow on side on dock we were on.

Ill look for video

[Conquistador_del_mar]

Yes sir I took it and ran it without the t-stat and not much change at all

I have a 140 installed...water flow looks good I ran it when we got home on the hose and it ran fine.

I changed the front water pump, impeller, all hoses, t-stat neck, and new guage...is there anything else I need to change? and why only at idle?
does the tilt/trim have anything to do with it because outdrive was up alot real shallow on side on dock we were on.

Ill look for video

You might want to see if it gets hot when idling with the drive down in deeper water. It could be that the drive to transom hose is getting crimped when you had the drive up in shallow water. Keep in mind that a water hose produces quite a bit of pressure so it might not allow that hose to crimp in that situation. It also could be that the drive pickup got a temporary piece of trash from the bottom if you were in really shallow water. Just a couple thoughts. Bill

[burgettw]

You might want to see if it gets hot when idling with the drive down in deeper water. It could be that the drive to transom hose is getting crimped when you had the drive up in shallow water. Keep in mind that a water hose produces quite a bit of pressure so it might not allow that hose to crimp in that situation. It also could be that the drive pickup got a temporary piece of trash from the bottom if you were in really shallow water. Just a couple thoughts. Bill

K. thats good info to know Im going to take a look at this afterwork and hopefully take it out if it dont rain, we have had some crazy weather around here

[burgettw]

Well no new news it just happens to rain everytime I try to take her out so will try again today...but has anyone else had this overheating problems and some more ideas how to solve I have tried everything

[VetteLT193]

before you replaced the impeller, was the old one missing blades? You might have a clog somewhere.

[mrfixxall]

I finally got a chance to take my boat out 5.7 chevy omc cobra outdrive and ran good all day till battery starting getting weak so while sitting at dock at idle for about 5-7 mins maybe to go get another battery when I got back it was like 210 I thought I had overheating problem done but I am running out of ideas to do I have changed every water item on my boat and it runs about 180 or 190 everyone is telling me it should not run more than 160 why is this or what is is supposed to run?

Thanks for yall help


What kind of drive are we talking about?:) What deg thermostat did you put in?

[burgettw]

What kind of drive are we talking about?:) What deg thermostat did you put in?

Na no blades missing just a little bit of rubber around the metal housing and the outdrive is a OMC cobra with a 5.7 chevy and 140 t-stat

[mrfixxall]

Na no blades missing just a little bit of rubber around the metal housing and the outdrive is a OMC cobra with a 5.7 chevy and 140 t-stat

on the port side(left) theirs a cobra sticker,is it still their? if its missing then their should be a big flat head straight blade screw(looks like the one on the dip stick behind it..gently push on it whyle its running on the hose and see if water comes out from behind it..its a plastic plug that is sanwiched between the screw and a few o-rings..that little plug goes into port where the water goes into the engine...

[burgettw]

on the port side(left) theirs a cobra sticker,is it still their? if its missing then their should be a big flat head straight blade screw(looks like the one on the dip stick behind it..gently push on it whyle its running on the hose and see if water comes out from behind it..its a plastic plug that is sanwiched between the screw and a few o-rings..that little plug goes into port where the water goes into the engine...


Its missing and welded shut if Im talking about the right thing???? On the outdrive?

[mrfixxall]

Its missing and welded shut if Im talking about the right thing???? On the outdrive?


yes it in the water port..did you put the thermostat in the rite part of the housing? i have seen where people have put 2 thermostats in their motore because they didnt see the one up inside the thermostat housing..

[burgettw]

yes it in the water port..did you put the thermostat in the rite part of the housing? i have seen where people have put 2 thermostats in their motore because they didnt see the one up inside the thermostat housing..

No sir there is only one and I think its in the right spot its in the neck on the water housing it fit snug in the hole and was to small for the other hole so I put it in there...(its where it was when I got the boat) hopefully they had it right

[Phil S]

i can't remember whether it was an overheating issue or something else, but it seems like i remember reading a thread on here about engine cooling / water hoses, and it seems like they had replaced them all and put them back in the same way they found them, but it turned out they had been routed wrong by the previous owner (or something like that). they posted a picture of the engine with the hoses all connected, and someone here quickly noticed the incorrectly routed hoses & explained the correct "path" for the hoses.....you might one to post up a picture of your engine if you can...hopefully it will be something simple as it sounds like you have a whole new cooling system installed..:crossfing:

just a thought...
Phil

[burgettw]

So I'm thinking about selling it anyone interested lol :yes: maybe thinking about trading it for another boat but no way I could get enough out of it to buy another Donzi around here they are exensive when you can find one

[burgettw]

i can't remember whether it was an overheating issue or something else, but it seems like i remember reading a thread on here about engine cooling / water hoses, and it seems like they had replaced them all and put them back in the same way they found them, but it turned out they had been routed wrong by the previous owner (or something like that). they posted a picture of the engine with the hoses all connected, and someone here quickly noticed the incorrectly routed hoses & explained the correct "path" for the hoses.....you might one to post up a picture of your engine if you can...hopefully it will be something simple as it sounds like you have a whole new cooling system installed..:crossfing:

just a thought...
Phil


k. Ill try and get a picture tonight because the diagram in the book doesnt even look like the neck thats on mine and it only shows half of it

[cutwater]

I think cutwater went through this about a year ago... might want to search.

What did you change?
What Thermostat do you have installed?
What does the water flow look like (Cutwater has his Minx on youtube that shows the water flow so you can compare)

An easy check to see if the T-stat is the issue is to just pull it out and see how it runs without one.

http://www.youtube.com/watch?v=AlknqRKki2E&feature=related
Although the flow is a little weak... I'll explain later... Mine did not overheat at idle.


Yes sir I took it and ran it without the t-stat and not much change at all

I have a 140 installed...water flow looks good I ran it when we got home on the hose and it ran fine.

I changed the front water pump, impeller, all hoses, t-stat neck, and new guage...is there anything else I need to change? and why only at idle?
does the tilt/trim have anything to do with it because outdrive was up alot real shallow on side on dock we were on.

Ill look for video

Wow, that's a pretty exhaustive list. How old is your exhaust/risers? Are they corroded? When you took the t-stat housing off, was there a lot of rust/scale?


Na no blades missing just a little bit of rubber around the metal housing and the outdrive is a OMC cobra with a 5.7 chevy and 140 t-stat

That's the o-ring seal on the impeller housing. Make sure it's intact and properly fitted with a little grease so that you aren't getting air bubbles in there.


on the port side(left) theirs a cobra sticker,is it still their? if its missing then their should be a big flat head straight blade screw(looks like the one on the dip stick behind it..gently push on it whyle its running on the hose and see if water comes out from behind it..its a plastic plug that is sanwiched between the screw and a few o-rings..that little plug goes into port where the water goes into the engine...

What the heck are you talking about Fixx?? Haha, :wink: :bonk: :wink: Please explain further, I'm lost on this one...


So I'm thinking about selling it anyone interested lol :yes: maybe thinking about trading it for another boat but no way I could get enough out of it to buy another Donzi around here they are exensive when you can find one

Don't give up! It took me forever to fix mine, but I learned a lot in the process. My problem ended up being an intermittent circulation pump failure. I guess what must have been happening was that the blades locked up at moderate speeds, then when revved or not under load (at idle, only needing small amount of water) they would free up, or at least let some water pass through. I went to a crossover system (completely eliminating the circ pump) and never had another problem again.

[Forrest]

. . . . How old is your exhaust/risers? Are they corroded? When you took the t-stat housing off, was there a lot of rust/scale? . . .

Make sure that your exhaust risers' water-jackets are not plugged up with rust and flow water easily. A blockage in an exhaust riser water-jacket will make any engine overheat, especially as the RPM goes up.

[mrfixxall]

What the heck are you talking about Fixx?? Haha, :wink: :bonk: :wink: Please explain further, I'm lost on this one...

Find a cobra drive and peel back the cobra emblem on the port side,their is a big ass screw behind it for checking to see if your inpeller is working but dont mess with it,if you unscrew it you will have to pull the drive to get it back together..

[techspecial]

Check my threads about this time last year...
It was weak springs on the ball checks in my t-stat housing.
At low RPM's all the water was blowing through my manifolds because the spring pressure wasn't diverting it through the motor. I have a late (86) eighties setup. Kicked my butt for a couple of weeks!! I hope this helps!!!

[cutwater]

Find a cobra drive and peel back the cobra emblem on the port side,their is a big ass screw behind it for checking to see if your inpeller is working but dont mess with it,if you unscrew it you will have to pull the drive to get it back together..

Ok, makes sense... My Cobra drive has never had a sticker on it so I was a little confused. :boat:

[cutwater]

Check my threads about this time last year...
It was weak springs on the ball checks in my t-stat housing.
At low RPM's all the water was blowing through my manifolds because the spring pressure wasn't diverting it through the motor. I have a late (86) eighties setup. Kicked my butt for a couple of weeks!! I hope this helps!!!

Good tip, but the OMC t-stat housings are a different architecture, I don't think this will apply to his setup :thumbsup:

[burgettw]

Good tip, but the OMC t-stat housings are a different architecture, I don't think this will apply to his setup :thumbsup:

Well again yesterday tried to take it out and it rained and rained, so didnt even get a chance to get out and get a picture. but anyways my risers and manifolds are new like 4 months old dont think they are stopped up, and ill check the t-stat but it did it without it and it opened up on the stove at 150 so dont think that is the problem... im at a lost here guys but the thing is it ran fine when I got back home so it may be trash but cant take it back out becuase of the rain maybe will have better luck today

[mrfixxall]

Well again yesterday tried to take it out and it rained and rained, so didnt even get a chance to get out and get a picture. but anyways my risers and manifolds are new like 4 months old dont think they are stopped up, and ill check the t-stat but it did it without it and it opened up on the stove at 150 so dont think that is the problem... im at a lost here guys but the thing is it ran fine when I got back home so it may be trash but cant take it back out becuase of the rain maybe will have better luck today


you say it over heats at idle? is your idle to low for it to cause it to not pump enough water or mabe you have a bad oring on the drive gasket and it may be pimping the water else where..

[burgettw]

you say it over heats at idle? is your idle to low for it to cause it to not pump enough water or mabe you have a bad oring on the drive gasket and it may be pimping the water else where..

Not sure the engine seems to idle just fine not to low and all the gaskets on drive were replaced when rebuilt...where could it be pumping the water? and I got flow coming through the engine

[mrfixxall]

Not sure the engine seems to idle just fine not to low and all the gaskets on drive were replaced when rebuilt...where could it be pumping the water? and I got flow coming through the engine

Try bumping the idle up a tad,it could make sll the differance in the word..sit at the dock at idle and uer the throttle lever and bump it up to 800 rpms and see if it still overheats..

[burgettw]

Try bumping the idle up a tad,it could make sll the differance in the word..sit at the dock at idle and uer the throttle lever and bump it up to 800 rpms and see if it still overheats..

K. thanks! Will try

[cutwater]

Also, while your engine is cold, disconnect the inlet hose to the t-stat housing (coming from the outdrive) and run the engine at idle. Let this water dump into an empty 1 gal milk jug, and time how long it takes to fill up.

My Cobra drive took about 15 seconds at idle to pump a gallon, although that might be a little higher than normal.