Overheating Twin Rebuilt Loopers

[hi_five]

Back in May I purchased a 32'1988 Chris Craft Stinger. I had both engines rebuilt (1997 Johnson 225 Loopers) standard rebuild 20 thousands over, with Wiesco pistons at a local marina. After the break in period I noticed both motors were overheating after about 15 mins on plane. I've had them back several times for various fuel related problems each time fixing one thing or another. We decided to removed the VRO and I mix the oil directly to the fuel in the tank. Today he ordered electric fuel pumps stating that they are inexpensive and very reliable and is intending to eliminate the diaphram fuel pump altogether. However, they are still unable to figure out why both motors are overheating. The mnotors have a typical cylinder head temp sending units (one wire) they are attached to gauges which are colored green and red. Both will run hot and sound the horn after about 15 mins of wide open thottle (about 5000-5500)rpm. I have tried to play with the tilt and trim; it seems if the motors are tucked all the way under the temp is high, but not enough to trigger the warning horn, but I loose knots on the top end as a result. usally I run about 40 knots trimmed out. The mechanic who rebuilt the power heads first checked the water pumps, then removed the screens from the lower units and enlarged the water pickup holes. This seemed to help a little but it still overheats. I added water pressure gauges and have 8 psi. Does this seems too low?. By this time I frustrated. I asked if the thermostat could be the culprit, or the head gasket. The mechanic insists that these are not likley candidates. He wants to lower the motors on the Armstrong Bracket 1 inch, stating that he noticed a flucuation in the water pressure gauge during testing, thinking the top water inlet is sucking air. I need some help guys. He said if this does not work he wants to put low water pickup tubes or some sort of bullet on the lower unit with a SS hose to the power head to flow more water at the tune of $300.00 each. Owee. Does anyone have any thing I can suggest or try myself? Is 20 over too much for a looper? And why does the water not "****" it seems to slowly flowout? Should the pumps produce more than 8psi? At what temperature doo the warning horns sound?<br />Thanks for any help...

 

[hondon]

Re: Overheating Twin Rebuilt Loopers

Lowering the engines an inch may well help you.You will feel this however in your top end but it is a trade off you might have to endure.Also ,in the trial runs ,did that tech actually monitor head temp,or did he just take the guage or horns word for it?Water pressure gauges can be sketchy,especially if the pickup tubes make a long run to the gauge.Color codeing on your temp senders leaves me a little confused.That ain't stock.

 

[clanton]

Re: Overheating Twin Rebuilt Loopers

The temp sensor on the port side of engine has 2 wires 1 tan, 1 black/white. The starboard side has 1 tan wire. If the engine is running hot it should be setting S.L.O.W. which reduces the rpms to 2500, was this bypassed. The VRO pump should pump plenty of fuel if the fuel system is installed correctly. I agree with bypassing the oil side of the pump and mixing the oil and fuel in fuel tank. OEM water pumps may help. Engines are probley to high on bracket.

 

[Dhadley]

Re: Overheating Twin Rebuilt Loopers

Your motors will not live at 8 psi. Make sure you are reading from the correct place. On loopers you read from the adaptor plate not "T" into the overboard (pee) hose. <br /><br />Be very careful with electric pumps. Your insurance company will have a stroke if they find out that you have them and they are not hooked to some sort of automatic shut off device. If you use them do not remove the stock fuel pumps. They will act as a pressure regulator and prevent the carbs from overflowing. <br /><br />You may need low water pick ups to retain your performance but lets look at a couple of things first. <br />1- Is the warning horn for heat? You never mentioned it going into S.L.O.W. but did talk about fuel problems. Could the horn be for fuel pressure?<br />2- Verify the correct location of the hose for the water pressure gauge.<br />3- There are scoops made for your lower units. <br />4- The motors should be toed in 1/16" to 3/16". This is extremely important.<br /><br />It is not uncommon to plug the top two inlets on the outside of each gearcase and the top hole of the inside of each gearcase. There is even room to add another hole at the bottom thus lowering your intakes without lowering the motor.<br /><br />You should have well over 20 lbs of water pressure. Probably over 30. <br /><br />Let us know how you make out!

 

[hi_five]

Re: Overheating Twin Rebuilt Loopers

hondon- <br />The tech monitored the temp by pulling the cowl and feeling the heads. The color cde is basic, the needle on the gaug points to green or red green is at the bottom. As the temperature rises the needle procedes upward to the red. Then when the needle is at the top of red the horn sounds.<br />clanton- <br />I don't know what S.L.O.W. means. The baot certainly did not go to 2300 RPM and I will ask if it was disconnected tommorow when I pick it up.I realize that the lowering of the motor might help but my question then is, if the engines are too high on the bracket , why didn't anyone notice before now?<br />Dhadley-<br />I will ask where the psi gauges are getting there infomation tommorow and I thank you. I assume that the horn is for overheating because the temp gauges were topped out at red when the horn went off then the port motor would follow suit shortly thereafter. S.L.O.W. ??? Where can I find the SCOOPs for my motors? Iwill check the toe in also tommorow. I will ask about your solution of plugging and adding hole tommorow.<br /><br />I knew you guys would help. Thanks a million. Keep the ideas coming so I can defeat this and catch some GROOPER....

 

[Dhadley]

Re: Overheating Twin Rebuilt Loopers

^

 

[hi_five]

Re: Overheating Twin Rebuilt Loopers

Yesterday I went to the marina and helped replace the gauges on my boat. I checked the "Toe In " as suggested and it's 26.5 inches in front and 26.5 inches in back of the lower units. The psi gauge is "T'd" in at the plate not the Pee tube. As I said we replaced the color temp gauges w/ numeric ones. Fired off the engines one at a time and the temp was reading 180 Deg. not more than 15 secs after start-up? Could the sending unit be bad on both motors? Could the thermostats be stuck open? The motors were lowered 1 inch and I will try it out on friday 8/10/02 will let you know what happens.

 

[hi_five]

Re: Overheating Twin Rebuilt Loopers

HowieDean<br />We did lower the motors 1" see above thread. What are "Bullets"? I will try things the way they are and then try your Tape idea, Thanks...<br />Dhadley<br />Hoses are in good position. "Toe in" is as above thread. Both horns were going off at once Port soon after Starb went off. Steady horn, that did go off about 1 minute in nuetral. The electric fuel pumps are in now.

 

[clanton]

Re: Overheating Twin Rebuilt Loopers

If you are paying some one to do this work, I would change mechanics/techs.

 

[Dhadley]

Re: Overheating Twin Rebuilt Loopers

The motors should be toed in 1/16" to 3/16". Not straight ahead. Describe your water inlets and I will get you the part numbers for the water pick ups. Do you have 4 holes or one long intake?<br /><br />Let me know!

 

[hi_five]

Re: Overheating Twin Rebuilt Loopers

Dhadley<br />There are four holes one each side. I'll let you know how it does on Sat. Thanks again...<br />Clayton<br />That thought has crossed my mind...

 

[Dhadley]

Re: Overheating Twin Rebuilt Loopers

The kits are #398185. You will need 2 per motor. These are standard when rigging the Stinger or Scaarb. We toe in the motors to aim the water intakes at the most water taking in account the V of the hull and location of the lifting strakes. It also helps handling and performance. <br /><br />I prefer to fill the top 2 inside holes and the top outside holes and drill one more at the bottom. These hulls are fairly sensitive to engine height. We have used Bob's nose cones with the low water pick ups and were able to raise the motors and use better props. <br /><br />Its a bit unusual to have the holes in the counter rotating gearcase instead of the slot but the scoops will work on the holes. Post the model numbers if you can and top RPM's.<br /><br />Good luck!