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Author Topic:   OMC 115 (Rage) Thermostat & Poppet Valves

henrydbrown posted 07-31-2011 02:46 PM ET (US)
Hi,
As a matter of introduction, I inherited an inop Rage with the 115 OMC/ jet drive. Yes, I'm tracking it is the blacksheep but would appreciate any help.
I've gotten it to start using the fresh water adapter by rebuilding the starter & replacing the battery and cleaning all engine compartment connections. I've also fixed most of the wiring (no electrical was working) and am down to replacing the ignition switch (PO put a push button starter in) and I removed the thermostats prior to a test run in the actual water.
Out of concern for all the cracked head stories I've seen, I want to try to get maximum cooling so I'm going to start out by running it without thermostats. I've cleaned out the thermostat housing and am considering whether to leave those spring loaded valves in or not.
The water in Annapolis is 85 degrees right now.
Any thoughts would be welcome!
Hank
henrydbrown posted 08-02-2011 09:09 PM ET (US)
I guess no one out there has a mid-nineties OMC 90 or 115...
I just re-installed the thermostat housing after cleaning it and the inlet side on the motor plate. I left the thermostat holes open but reinstalled the springs and plastic valves/ grommets figuring they must serve some purpose in maintaining pressure. I did not torque it down to 60-75 ft/lbs as the service manual instructs; I just couldnt risk breaking one of those off and having to pull the motor then drill it out.
I'll keep myself posted on my progress in this forum. Test run on Saturday.
RandyV posted 08-04-2011 09:59 PM ET (US)
I had a Rage 15 with the OMC 115 and loved it (have since upgraded to a Montauk). After doing some repairs from previous owner neglect & ignorance, I removed the thermostats and the poppets. I ran this engine in Lake Erie / Detroit River very early spring with no poppets or thermostats installed and had no cold running problems so with that I assumed there would be no warmer water low temp problems either. I see no reason to keep the poppets installed in this engine. Mine ran great, cooled properly started ok and when warmed up, started excellent and ran like a dream. It was very fun for tubing, jumping waves in Lake Michigan when conditions were right and was even better in skinny water.
If it does not have a fresh water strainer installed for the cooling lines, get one installed ASAP. Check the cooling line from the jet drive all the way to the engine and make sure there are no shells, stones etc. causing a partial blockage. This is just a preventative check and might be good to do yearly if you run in shallow water at all.
A2J15Sport posted 08-05-2011 04:43 PM ET (US)
That "crossflow" engine defintely needs the thermostats in place.
Without them, you run the risk of uneven block cooling. That can result in scored pistons, etc.
A couple things:
1. I would also pull the heads and look for the water diverters. Make sure they are in place and where they are supposed to be.
2. I believe the stat. housing torque is in INCH pounds, not foot pounds.
henrydbrown posted 08-07-2011 07:11 AM ET (US)
"IN/LBs not FT/LBs" That is funny. I'll need to recheck the manual. So is 60 in/lbs = to 5 ft/lbs?
The contradictory guidance is troubling -
With poppet valves in and thermostats out I ran the Rage yesterday for about 20 minutes. I let it idle on the trailer for 5 minutes then ran it at higer RPM on the trailer for 5 minutes. The Gauges are not working and I'm not confident the overheat warning alarm is working even though the PO says it does. I used an infrared temperature sensor and took a measurement on the top of the head (same place as indicated in the service manual) every minute or so. Once it warmed up my readings were consistently in the 160s. I had one 177 out of dozens that were in the 160s - I don't know if it was a false reading or an anomoly.
I'll be working on the gauges and alarm today.
seahorse posted 08-07-2011 07:48 AM ET (US)
You have to check the cylinder head temperatures while the boat is in the water, not on a hose, to be accurate.
It is best to leave the thermostats in as water pressure is needed to fully absorb the heat from the motor. Make sure the white plastic pressure relief valves are not sticking inside the rubber grommets.
One hint for improving the cooling those motors is to replace the 90° elbow fitting on the pump body, where the engine cooling water hose attaches, with a straight fitting. That way bits of rock or shell won't lodge in the 90° bend and restrict the water flow to the motor.
madfinnhockey posted 08-07-2011 08:58 PM ET (US)
I've had no overheating problems with my 95 Rage 15 that I've had for at least 5 years now, and I have not removed any of the thermostats or poppet valves. I run the boat the in relatively cool ocean waters of NH and Mass.
You mention the overheat alarm, if you have an ignition switch (key) as soon as you turn the key to the "on" position the overheating alarm buzzer should sound for just a second.

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Author	Topic: OMC 115 (Rage) Thermostat & Poppet Valves
henrydbrown	posted 07-31-2011 02:46 PM ET (US) Hi, As a matter of introduction, I inherited an inop Rage with the 115 OMC/ jet drive. Yes, I'm tracking it is the blacksheep but would appreciate any help. I've gotten it to start using the fresh water adapter by rebuilding the starter & replacing the battery and cleaning all engine compartment connections. I've also fixed most of the wiring (no electrical was working) and am down to replacing the ignition switch (PO put a push button starter in) and I removed the thermostats prior to a test run in the actual water. Out of concern for all the cracked head stories I've seen, I want to try to get maximum cooling so I'm going to start out by running it without thermostats. I've cleaned out the thermostat housing and am considering whether to leave those spring loaded valves in or not. The water in Annapolis is 85 degrees right now. Any thoughts would be welcome! Hank
henrydbrown	posted 08-02-2011 09:09 PM ET (US) I guess no one out there has a mid-nineties OMC 90 or 115... I just re-installed the thermostat housing after cleaning it and the inlet side on the motor plate. I left the thermostat holes open but reinstalled the springs and plastic valves/ grommets figuring they must serve some purpose in maintaining pressure. I did not torque it down to 60-75 ft/lbs as the service manual instructs; I just couldnt risk breaking one of those off and having to pull the motor then drill it out. I'll keep myself posted on my progress in this forum. Test run on Saturday.
RandyV	posted 08-04-2011 09:59 PM ET (US) I had a Rage 15 with the OMC 115 and loved it (have since upgraded to a Montauk). After doing some repairs from previous owner neglect & ignorance, I removed the thermostats and the poppets. I ran this engine in Lake Erie / Detroit River very early spring with no poppets or thermostats installed and had no cold running problems so with that I assumed there would be no warmer water low temp problems either. I see no reason to keep the poppets installed in this engine. Mine ran great, cooled properly started ok and when warmed up, started excellent and ran like a dream. It was very fun for tubing, jumping waves in Lake Michigan when conditions were right and was even better in skinny water. If it does not have a fresh water strainer installed for the cooling lines, get one installed ASAP. Check the cooling line from the jet drive all the way to the engine and make sure there are no shells, stones etc. causing a partial blockage. This is just a preventative check and might be good to do yearly if you run in shallow water at all.
A2J15Sport	posted 08-05-2011 04:43 PM ET (US) That "crossflow" engine defintely needs the thermostats in place. Without them, you run the risk of uneven block cooling. That can result in scored pistons, etc. A couple things: 1. I would also pull the heads and look for the water diverters. Make sure they are in place and where they are supposed to be. 2. I believe the stat. housing torque is in INCH pounds, not foot pounds.
henrydbrown	posted 08-07-2011 07:11 AM ET (US) "IN/LBs not FT/LBs" That is funny. I'll need to recheck the manual. So is 60 in/lbs = to 5 ft/lbs? The contradictory guidance is troubling - With poppet valves in and thermostats out I ran the Rage yesterday for about 20 minutes. I let it idle on the trailer for 5 minutes then ran it at higer RPM on the trailer for 5 minutes. The Gauges are not working and I'm not confident the overheat warning alarm is working even though the PO says it does. I used an infrared temperature sensor and took a measurement on the top of the head (same place as indicated in the service manual) every minute or so. Once it warmed up my readings were consistently in the 160s. I had one 177 out of dozens that were in the 160s - I don't know if it was a false reading or an anomoly. I'll be working on the gauges and alarm today.
seahorse	posted 08-07-2011 07:48 AM ET (US) You have to check the cylinder head temperatures while the boat is in the water, not on a hose, to be accurate. It is best to leave the thermostats in as water pressure is needed to fully absorb the heat from the motor. Make sure the white plastic pressure relief valves are not sticking inside the rubber grommets. One hint for improving the cooling those motors is to replace the 90° elbow fitting on the pump body, where the engine cooling water hose attaches, with a straight fitting. That way bits of rock or shell won't lodge in the 90° bend and restrict the water flow to the motor.
madfinnhockey	posted 08-07-2011 08:58 PM ET (US) I've had no overheating problems with my 95 Rage 15 that I've had for at least 5 years now, and I have not removed any of the thermostats or poppet valves. I run the boat the in relatively cool ocean waters of NH and Mass. You mention the overheat alarm, if you have an ignition switch (key) as soon as you turn the key to the "on" position the overheating alarm buzzer should sound for just a second.