98 GTX LTD overheating... should I remove top of head? (solved)

[Grim]

I have been chasing a problem with over heating for a while, did some fixes and I am waiting on the weather to get just a little better, I was thinking of pulling the top of the head off to see if there is any dirt/debris in the cavity where the water flows around the head. It may be a reason for it overheating.....I think?

I have read about head bolts breaking and don't want that to happen. Is it a big problem with 951 engines. It is suppose to have about 30 hrs on rebuilt engine but sat for 9 years, no salt water. Would it be worth the risk or should I just be patient and see if it is fixed with all the other little stuff I've done to it. I am also curious to see what the top of the pistons look like and the cylinder walls. What's my risk?

 

[mikidymac]

The 951 can be a pain to reseal the head and you need anew gasket, not easy like the 787-580 engines.

I would blow out all hoses and fittings with compressed air ,flush on the hose (Never have hose on with engine off) and verify all your hose routing is correct twice before pulling the head.

 

[Grim]

I got all new hoses and flushed it about a dozen times, always engine on, water on, water off, engine off...style. Changed out a wrong spark plug and adjusted the pressure regulator (it is only getting hot when I go over about 3K to 4K, if I'm at idle or low speed it is just fine.) Checked flow in each line, all is good. Haven't checked it since the spark plug and regulator adjustment...little too cold, even in Fl.

Crossing my fingers that did it.

 

[mikidymac]

Never adjust the water regulators, they are factory set.
They are not a tuning device like the RAVE valves on the engine.

Pump cavitation can cause overheating at higher rpm. Check your impeller and wear-ring.

 

[Grim]

Never adjust the water regulators, they are factory set.
They are not a tuning device like the RAVE valves on the engine.

Pump cavitation can cause overheating at higher rpm. Check your impeller and wear-ring.

Yeah, I leaned not to mess with the regulator after I had tinkered with it. No one seems to know what that factory setting is either. Trying to get it back right.

I'll take a good look at the impeller and wear ring.

 

[Poormanracing]

They usually get clogged in the elbow going into the head.you could either remove the head and clean it that way or pull the temp sensor run a thick wire into it and try and clean it out that way.but me I would take the head off to see if it's clogged

 

[Grim]

They usually get clogged in the elbow going into the head.you could either remove the head and clean it that way or pull the temp sensor run a thick wire into it and try and clean it out that way.but me I would take the head off to see if it's clogged

I did pull off the temp sensor and look down in there , but it is shallow, it must angle left and right soon after the sensor. Are you saying I should run a wire left and right , if so how far will it normally go?

 

[Poormanracing]

I did pull off the temp sensor and look down in there , but it is shallow, it must angle left and right soon after the sensor. Are you saying I should run a wire left and right , if so how far will it normally go?

It goes in and around the head you can't hurt anything poking in there also blow compressed air while you are pok8ng around.there is a block drain it's a clear hose while blowing make sure it's coming out the drain.

 

[Grim]

Ok, so I had a friend who had a borescope but I couldn't get it past the opening at the temp sensor. Any ever successfully borescope through there? I assume I need a borescope with a small or flexible head on it....anyone know of a unit, that doesn't break the bank?

 

[mikidymac]

You aren't going to get in there with a bore scope.

 

[Grim]

You aren't going to get in there with a bore scope.

Yeah, I just looked at some videos on top end builds and see there isn't much room in there at all, don't even think I could go through the water inlet port and see anything.....any ideas how to inspect without taking top of head off? Any way to do a powerful flush maybe right at the engine without flooding it?

 

[mikidymac]

I typically use compressed air to break things apart then flush on the hose.

How do you know you are overheating?
Is water flowing out the pisser when in the water running?

 

[Grim]

I typically use compressed air to break things apart then flush on the hose.

How do you know you are overheating?
Is water flowing out the pisser when in the water running?

I got the temp alarm, so I went back out and had my meter, which has a temp probe on it and ran it. I also have a infrared thermometer, used both It got above 200 when I went over 3500 rpm (ish) for any sustained time, not more than 3 or 4 mins maybe before alarm hit. If I just idled it would go back down within a minute or two and if I stayed low rpm it was fine. I would go back up to speed and it would get hot again.
One my may den voyage, one of the pissers were blocked, I unclogged it right away, I had cleaned it several times at home while on the hose. Both now are pissing well, but I noticed when the engine is hot the water out the pisser is hot too, hot to the touch, maybe 3 second hold before I cant handle the temp.
The ski came from Oklahoma, the red dirt there is notorious for clogging crap up. That is why in the back of my head I get this idea, maybe dirt got into the cavity for the pistons and therefore not enough water is circulating....but the pipe gets hot too!
I have systematically checked each water hose, using the garden hose as a water source, it took time but I had no issues, water is flowing well out of each one. Engine is cool to touch as well, but it is only at idle. I'm lost for where the problem could lie.

 

[mikidymac]

It sure sounds like it is your pump not moving enough water.

I would pull the pump and check the impeller, wear ring and the rubber seal between the pump and bulkhead.

 

[Grim]

It sure sounds like it is your pump not moving enough water.

I would pull the pump and check the impeller, wear ring and the rubber seal between the pump and bulkhead.

Ok, I'll do that, got a few weeks before I can get it on the water.

 

[Poormanracing]

I would just pull the head.very few have a problem going back together and sealing.its not worth the hassle of trying to fit a borescope in there.are any exhaust hoses burning?

 

[Grim]

It sure sounds like it is your pump not moving enough water.

I would pull the pump and check the impeller, wear ring and the rubber seal between the pump and bulkhead.

So, just out of curiosity, and I like to know whys, are you thinking there is some cavitation and it is not allowing enough water into the intake hose at higher speeds? It certainly has vey good get up and go.....but

 

[mikidymac]

Yes. The cooling system is dependent on the jet pump.
If it still has good takeoff and speed then it could be a blockage at the pump or leaking pressure at the seal between the pump and hull.
I only say this because it seems like your hoses are open and it is good on the hose.

 

[Grim]

Yes. The cooling system is dependent on the jet pump.
If it still has good takeoff and speed then it could be a blockage at the pump or leaking pressure at the seal between the pump and hull.
I only say this because it seems like your hoses are open and it is good on the hose.

I finally was able to get under it and take the grate off to inspect the propeller and wear ring. I used a .040 feeler gauge and couldn't get in between the blades and wear ring....but I did notice that my wear ring has grooves in it.....pretty deep ones...and it looks like it is brass!!
Here are pictures, what do you think. I read another members thread about having issue replacing it because he had a brass/bronze wear ring...it was a unicorn...Am I in the same boat? or maybe it isn't brass/bronze!
On the picture you can see light gray lines in the wear ring, those are the grooves. I think this is the original wear ring too.

 

[Poormanracing]

The water regulator only adjust water going to your exhaust and is used to tune the exhaust.you won't really hurt anything just change the tuning a little bit.cant see the grooves in wear ring but I don't see any burning or dull spots on the impeller showing cavitation.get the impeller off and show more pictures.

 

[Poormanracing]

Judging by the leading edge of impeller it shows signs of vegetation getting chewed up.if that's the case pull the dam head and look

 

[Grim]

The water regulator only adjust water going to your exhaust and is used to tune the exhaust.you won't really hurt anything just change the tuning a little bit.cant see the grooves in wear ring but I don't see any burning or dull spots on the impeller showing cavitation.get the impeller off and show more pictures.

Let me ask you this, if the regulator isn't adjusted well would it cause the engine to over heat only at higher RPM? My guess is no, but I'm no expert ether.

 

[Grim]

Judging by the leading edge of impeller it shows signs of vegetation getting chewed up.if that's the case pull the dam head and look

So what you are saying is there could be debris in the head cavities, taking up space, that would cause the over heating at higher RPMs? It seems plausible for sure.

 

[Poormanracing]

No has nothing to do with engine temp.you have a feed line going in then a hose going to the mid pipe.it tunes the return pulse to the exhaust port opening and cools the pipe to make it think it's smaller for better top end flow.if it was my essed up you would be melting exhaust lines and the rubber coupler.

 

[Poormanracing]

So what you are saying is there could be debris in the head cavities, taking up space, that would cause the over heating at higher RPMs? It seems plausible for sure.

Yes correct.i would pull the head and see what you got going on.i have never had a problem with leaking head gaskets