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Overheating concerns for 8V92 - need advice - Printable Version

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RE: Overheating concerns for 8V92 - need advice - 77newell - 07-20-2015

A couple thoughts. It takes fuel to energize the turbo to produce boost on the 2-stroke engines, so based upon your boost numbers I would conclude your fuel supply is more than adequate.

Gauges and senders can go funky with time. If the digi-panel is hooked to the same sender as the analog gauge then all you need to do is determine which gauge is dependable and an IR gun can help with that.

Since your fan is direct drive your air through the radiator is dependent on engine RPM. At 15psi boost and 1600 you may not have enough airflow to keep up, but verify your gauge accuracy first. Keeping a 2-stroke rev'd and cool is all you have to worry about.

RE: Overheating concerns for 8V92 - need advice - Flick - 07-20-2015

(07-20-2015, 07:39 AM)77newell Wrote:  A couple thoughts. It takes fuel to energize the turbo to produce boost on the 2-stroke engines, so based upon your boost numbers I would conclude your fuel supply is more than adequate.

Gauges and senders can go funky with time. If the digi-panel is hooked to the same sender as the analog gauge then all you need to do is determine which gauge is dependable and an IR gun can help with that.

Since your fan is direct drive your air through the radiator is dependent on engine RPM. At 15psi boost and 1600 you may not have enough airflow to keep up, but verify your gauge accuracy first. Keeping a 2-stroke rev'd and cool is all you have to worry about.

ok so then on flat land 1700 rpm at 65 running gauge temp 185 and digi 175. On hills gear down to keep rom close to 2000 and temp below 200?  Should I trust that temp light if it comes on?


RE: Overheating concerns for 8V92 - need advice - Fulltiming - 07-20-2015

I wouldn't wait for the light to come on but IF it comes on IMMEDIATELY pull to the side of the road, put the transmission in neutral and keep the rpms up around 2000 to cool that puppy down.  Don't shut the engine down or it will get even hotter.

RE: Overheating concerns for 8V92 - need advice - Richard - 07-20-2015

Todd,

You have some great advice in all the input from the gurus. Let me see if I can organize it in a logical sequence to help.

First thing to do is determine what gauge you are going to use to make your decisions. Use the IR gun and shoot the radiator at inlet and outlet necks. If the surface you are shooting is not black, then spray it with flat black paint to get the most accurate reading. You could also measure the outlet of the water pump. Now that you have confidence in the dash instrument of choice. You can decide if you have a cooling problem or not. If you want another confirmation, open the radiator cap, and insert a digital thermometer. It's well established that most of us don't trust the analog gauges on the dash any longer. So, you need to affirm if the digipanel is giving you good info.

Second, cleaning the radiator is never a bad idea. As others have said, don't go crazy with a pressure washer or you'll bend the fins.

Third, use the shifter and keep the RPMs up on the climbs. The two stroke engines do not like to be lugged (low RPM and heavy load). Running them at higher RPM helps with cooling in two ways. The obvious is that it speeds up the fan. The less obvious is that higher RPM pulls more air through the intake and out the exhaust. That increase in air flow through the engine has more effect than you would guess.

Sorry, for just repeating what others have said.

RE: Overheating concerns for 8V92 - need advice - ccjohnson - 07-20-2015

As an add on to Richard, make sure that radiator/cooling system is not under pressure when you remove radiator cap. Be careful as spewing hot liquid & stream can cause severe burns.

RE: Overheating concerns for 8V92 - need advice - Flick - 07-20-2015

Engine was ok to Bozeman. Then transmission got smoking hot and would not shift. Barely got off and it seized. Think I am about done with RVing. Too much for my heart and wallet.
Now I am trying to salvage my families vacation and my wife's birthday that we were supposed to spend in West Yellowstone.

We will see what the shop says that towed it to Belgrade, MT.

RE: Overheating concerns for 8V92 - need advice - HoosierDaddy - 07-20-2015

I understand how you feel, Todd. The added stress of keeping an RV going when you are supposed to be vacationing is very real to me as well. I have heard more experienced RV'ers (mostly fulltimers) say they have just learned to "roll with it" when they have a break down and try to enjoy experiences that were not planned.
The transmission problem explains a lot about what you were experiencing. Reading back over your posts indicates that something just didn't "feel right" to you. The Allison is a tough transmission. Hopefully it wont be an expensive repair.

RE: Overheating concerns for 8V92 - need advice - Flick - 07-20-2015

I got a hotel and took my kids swimming so they could relax. Tough day for the worrying. My wife called every hotel in West Yellowstone and finally found one. We will head down tomorrow. She got all call from the garage. The guy said the transmission is burned up from what he can see. He is calling in the morning with more details but he told Dawn 95% of the time we are better off with a new transmission. Must not be much more and comes with an warranty. We will see.

I am so tired of thinking about all of this that I cannot believe I am going to ask more questions. But here goes. Tom said the transmissions are built to handle the high RPM of 2000 I was trying to maintain on hills which was a speed of about 50. So if the transmission was slowly dying would that create stress on the engine and the temps I was seeing?
   

RE: Overheating concerns for 8V92 - need advice - HoosierDaddy - 07-20-2015

2000 RPM will not hurt the transmission. It appears that the trans was experiencing a failure which caused it to slowly bind up. The added load of a failed bearing would cause the engine to work harder and cause boost and heat to rise more than normal. I'm confident that your vigilance prevented engine damage.

RE: Overheating concerns for 8V92 - need advice - Richard - 07-20-2015

Sorry to hear of your troubles. Really sorry. I think all the gurus feel the stress of chief coach mechanic whilst not impacting any of the passengers in any way.

Tranny seizing up could cause engine to work harder. I just wonder if this was your first time climbing any grades of significance? In other words, was the engine running hotter than you had experienced on grades, or was this a new situation for you and the coach.

Have the mechanic check the transmission for any water in the tranny fluid. I am assuming you have a tranny cooler in your radiator like the later models. Water breaching the cooler and making it's way to the tranny is bad juju to an Allison. Not trying to scare you, just making sure you don't put in a new tranny and lose it too.