2002 Ford GT40 overheating

[TQs for life]

My engine temp ran at idle around 190-200 degrees and went immediately back to 140 at speed. I inspected my strainer, removed my t-stat, and changed out my impeller and I still have the problem. I read some other threads and saw a discussion about that one can possibly put a raw water pump in backwards on this model engine. I don't believe so. Can anyone tell me if that true? It doesn't seem to be the case as I look at the way it's mounted. Any other suggestions? I seems as though it might be that I'm not getting enough suck and possibly an air leak somewhere. Any help would be appreciated.

[s_kelley2000]

That sounds like the classic symptoms of an air leak to me. I would start by making sure the little O ring gasket in the strainer is present and seated correctly. If that doesn't solve the problem I would start checking and tightening hose clamps from the raw water intake and work your way back. If any of the hoses are dry rotted or showing signs of wear then that could also be causing an air leak.

You mentioned removing the thermostat. You put it back or replaced it with a new one right? It's not a good idea to run without one.

[TQs for life]

Shawn,
Thanks for your reply. I will do as you suggested. It jump happened to me this past weekend and I did everything I could think of sitting in the slip. I haven't replaced the t-stat yet, but plan to ASAP. My engine only has about 250 hours on it, everything (hoses) look brand new, but I'll carefully check them. Since I store my boat in my garage and will be diagnosing on land, I guess I shouldn't use the direct hose (pressured water) method to check, but instead do the garbage can approach (have it suck the water)? Any comment on the reverse orientation of the raw pump? Thanks again.

[s_kelley2000]

You can test the T-stat pretty easily by putting it in a pot of hot water and making sure that it pops open once it reaches or gets over the set temp. Pretty sure that will 143 degrees on your boat.

By garbage can method I assume you are talking about what I call the bucket method and yes that would be how I would run the boat on land and check for cooling issues.

Your boat doesn't have a fresh water flush on it does it? If it does have one, make sure the cap on the hose attachment is on tight as that is another common way that can allow air into the system.

I don't have a GT40 but I have heard that it is possible to put the whole water pump housing on upside down. If you did this I don't think it would cool down at speed but I don't know that for sure.

I should have asked this earlier but where there any broken or missing fins on the impeller that you removed? If so there is a good chance that one of these fins is stuck somewhere in the system and restricting water flow at idle causing your issue. The most common spot these broken fins end up seems to be right before the transmission cooler so I would check there first if any fins were missing.

[TQs for life]

Shawn,
I plan to do the bucket method to see if in fact I'm getting vaccum from the pump.

My boat does have the fresh water flush, I checked the cap and it was tight, thanks.

I really studied the pump orientation tonight, took it off, checked out how I had put it back on after changing out the impeller, and I believe I have it on correctly as I rolled the engine over and took notice to the direction of the pulley and the corresponding impeller movement and it was going the correct direction so that is good.

When I first inspected the impeller, it was in relatively good shape. All the fins were in tact and as I recalled, I put that one in probably two seasons ago and only ran my boat for about 10-15 hours since installing it. I went ahead and put in my new spare just to illiminate it as a cause. I did once experience on another boat the problem of an impeller failure and the fins breaking and causing the blockage problem you mentioned...that was a pain to diagnose.

I'm really starting to think that it must be some sort of an air leak as my pump and impeller seem to be fine, but that it's just not pulling water.

I did notice that my fresh water strainer swivals very freely between the fittings that secure the elbows. I'd swear that it has always been that way, but now I may be reading into things. Do you have one in your boat and does it move easily?

I think I will pull my boat out into the drive this weekend and set up the bucket and check out all the hose clamps and go from there.
Thanks.

[2001SAN]

my strainer swivels easily. don't think that would be it.

d.

[jasper]

Shawn is right on point. Those are classic symptoms of air being pulled into the system as stated above. Check all the hose clamps in the system to ensure they are snug and check the hoses for cracks. It all that checks out, you might check the gasket and o-ring in the raw water pump as well. Usually it is the strainer, hose clamp or cracked hose.

[jbach]

i agree with all of the above. definitely sounds like an air leak. i had the same problem early this season. i removed all hoses upstream of the RWP and re tightened adding a little vaseline to help get them back on properly. tighten them with a nut driver, not a screwdriver. check your strainer o ring. i put a little vaseline on the threads of that as well to help get it off/on. may as well replace your thermostat, it's $5, available anywhere.

i ended up having to replace my RWP as the seals were shot. check to make sure yours isn't leaking.

[ffmedic74]

Make sure that you still have the strainer gasket is in place too.

Sent from my SCH-I535 using Tapatalk 2

[s_kelley2000]

Shawn,
My boat does have the fresh water flush, I checked the cap and it was tight, thanks.

Fresh water flushes (especially the ones that contain plastic parts) commonly crack and can let air into the system. You will probably want to hook the hose up with this method as well to look for leaks.

[DanielC]

Here is a post about a flushing adapter I made.
As stated in the post, you can use this adapter to pressurize the water intake system up to the raw water pump. This makes most air leaks in that part od the system very obvious.
http://www.planetnautique.com/vb3/sh...ushing+adapter

[TQs for life]

Overheatng continued...

Fresh water flushes (especially the ones that contain plastic parts) commonly crack and can let air into the system. You will probably want to hook the hose up with this method as well to look for leaks.

Thanks for the additional thoughts, I check the plastic fittings for cracks as suggested. I did find a few of the hose clamps moderately loose and really tightened them up. I also re-checked that the o-ring in the strainer was in place and snug, which it was.

I really appreciate everyone's suggestions, thanks again.

[TQs for life]

I wanted to close this off and share what I found the problem to be...when the new impeller was installed, the pump orientation (inlet/outlet) was reversed when reassembled and so it was running backwards. Once it was reversed, it worked like it should. Embarrassing, but that was the problem. I wanted everyone to know the outcome. Thanks again for everyone's suggestions.

PS, the correct orientation for a Sherwood pump on a GT40 should have the "sight screw" facing towards the flywheel, not towards the outer side of the engine.

[charlesml3]

the pump orientation (inlet/outlet) was reversed when reassembled and so it was running backwards.

Wow, I'm surprised you were even able to get away from the dock with it like that. I would think that engine would overheat in just a minute or two.

Anyway, here's what you need to do: Now that the pump is installed properly, take some paint and put a big dot on the housing just behind the flywheel so you know which side is up. I used white, but that's only because it was what I had in the shed. That way the next time you put the pump in you'll get it right.

-Charles

[Mamigacz]

I wanted to close this off and share what I found the problem to be...when the new impeller was installed, the pump orientation (inlet/outlet) was reversed when reassembled and so it was running backwards. Once it was reversed, it worked like it should. Embarrassing, but that was the problem. I wanted everyone to know the outcome. Thanks again for everyone's suggestions.

PS, the correct orientation for a Sherwood pump on a GT40 should have the "sight screw" facing towards the flywheel, not towards the outer side of the engine.

Your not the only one this happend to. I don't have a GT40 engine, but I did the same thing on my previous boat after changing the impeller. As I was going across the lake I could smell something burning. I looked at the gauges and saw the temperature was higher than normal. The smell was from the rubber exhaust hoses burning.