ZR6 Over Heating

[KONAKING]

Hi guys I have a 2004 Tige yes Tige It has a ZR6 in it and I know Nautiques have a lot of those. I have been having some Heating up issues. It will run right at 160deg until I get on it. Then it climbs to 200 plus. If speed up to around high 30's I will overheat it. I have gone through the whole cooling system which is a closed system. Impeller is new I cant find any blockage. I even pulled apart the heat exchanger. The funny thing is as soon as I slowdown it drops right back to 160.

Any thoughts. Thanks for helping a Tige Owner

[gride]

do you ever get a rpm red. code?

[j2nh]

Did you replace the thermostat?

Remember you have two cooling systems on the boat.

Is the raw (river/lake) water portion over heating or is the closed loop overheating? Closed loop would be boiling the coolant and you would see it in the overflow reservoir.

Raw water would result in very hot exhaust hoses, be careful you don't melt them. If the hoses are getting hot and the impeller is in good condition chances are you have an air leak on the suction side of the pump. Make sure the gasket is on the raw water strainer, if its missing you can't get a good seal and it will leak air. Somebody posted recently that an elbow on the suction side was loose and air was leaking there.

[KONAKING]

do you ever get a rpm red. code?

Not sure what that is ? I have got the sensor going off before and it does restrict rpm until it cools.

[KONAKING]

Did you replace the thermostat?

Remember you have two cooling systems on the boat.

Is the raw (river/lake) water portion over heating or is the closed loop overheating? Closed loop would be boiling the coolant and you would see it in the overflow reservoir.

Raw water would result in very hot exhaust hoses, be careful you don't melt them. If the hoses are getting hot and the impeller is in good condition chances are you have an air leak on the suction side of the pump. Make sure the gasket is on the raw water strainer, if its missing you can't get a good seal and it will leak air. Somebody posted recently that an elbow on the suction side was loose and air was leaking there.

I have replaced the t-stat. I will check again for air leaks. I think it is the closed portion overheating due not enough flow through the heat exchanger. I pulled the raw water pump this spring and it did not look scored or bad?

Raw water strainer ? Do you mean at the pick up or at the pump?

[j2nh]

I have replaced the t-stat. I will check again for air leaks. I think it is the closed portion overheating due not enough flow through the heat exchanger. I pulled the raw water pump this spring and it did not look scored or bad?

Raw water strainer ? Do you mean at the pick up or at the pump?

Not sure if this is a PCM thing or a Correct Craft thing but just after the raw water enters thru the hull there is a clear plastic filter with a screen in it to clean out large contaminants from entering the raw water cooling system. If yours has this setup make sure the rubber gasket that seals the removable clear housing and the filter cap is in place. The assembly will not seal correctly without it and is guaranteed to give you a suction side air leak.

If your boat does not have the strainer I am wondering if you picked up weeds and they have plugged the exchanger. If the water pump is okay and the raw water side of the exchanger is clear then I would look for an air leak on the suction side (before impeller) of the raw water system.

[nms1991]

More than likely you do not have the water strainer in your system but check your trans cooler for blockage. Also if your engine is overheating at high speed you have a restricted water flow somewhere or a restricted exhaust system.

[gride]

with a closed system you probably do have a strainer. definitely check it for debris and the o-ring. has happened to me 3 times in 2 different boats.

[KONAKING]

Thanks guys I am in the process of checking every thing in the raw water side again. I will report back soon. The trans cooler is once place I have not checked before I will look closely at it. I have had the exchanger completely out before and there was some rubber form an old impeller and it was a pain to get it out of there.



Thanks again

[KONAKING]

Ok pulled everything off to the raw water pump. Found junk on the inlet side of the trans cooler. Leaves grass and some other junk. Did not seem like to much but maybe it was enough. Impeller looks brand new. Next step is take it on the wate r again

[teamseal]

OK!!!! Read this carefully!! When you turn on the key with out starting (key on engine off) With a cold engine. What does your temp gauge read?
You may have a ECT switch out of range. I just ran across this same symptoms with a 08 ZR-6 causing motor to go into power reduction and show excessive temp numbers at the gauge. The tel-tail was when the ignition was on with a cold motor the temp gauge read 165*.
Hope you find the culpret.

Good luck!

[KONAKING]

Gauge reads zero with key on and motor cool. I have suspected the ECT before but it seems to be working fine.

[KONAKING]

Ok so I took the boat out today and same old thing at idle or below 2 grand rpm it stays right around 175 deg. As soon as I start going faster it climbs to 200 and above. When I go back to idle it will quickly drop back to 175. My riser are warm but not hot. My hoses coming from the engine water pump to heat exchanger are hot. One side of the exchanger is hot and the other side is cool. I have the raw water pump out right now and the impeller looks brand new. Which way does it rotate? Or which way should the splines go. Looking at it as it would mount on the block the water comes in on the inside and exit out the out side. or on a v-drive enter on the left and exit on the right. So does it push the water all the way over the top and out?

Also if I had a bad stat or motor water pump I would think it would heat up even at idle. Possibly not getting the job done at the heat exchanger. I had it out before and cleaned but I am at a loss right now. Any ideas would be a help.

No noticeable scars on the inside of the pump and o rings look good. I also double checked all hose clamps on the suction before going out today.

[KONAKING]

At what temp do your zr6's run ?

[gride]

do you have coolant? what color?