Quote:
Originally Posted by folivier
The thing that has me concerned is normally on this bridge the temp only climbs 2-4 degrees. This time it climbed over 193. I guess I'm lugging the engine by driving 62, about 1700 rpm, in the hills. I'll have to learn to slow down on them hills. What concerned me was the temp climbing over 188 when I was accelerating up to 62. It's never done that before, it usually stays at 178-180.
I cleaned the radiator prior to this trip so it was clean before we left. Didn't burn any oil and level stayed the same.
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And this is the point in the post where ALARM bells should have started going off......for all of us.
You know your rig and how it performs and what is "normal". So if there is any change, regardless of whether or not it is "within normal operation" boundaries, you "gut" should have a lot of authority.
My money is on your GUT and I suspect tat something has changed.
Poiunts to consider:
The 2 cycle is sensitive to wear and as it ages it starts creating a huge amt of heat that the original design cannot deal with. Even at tasks it did easily. Lots of heat can mean a worn engine.
2 cycles can be worn out in just a few thousand miles because if they are lugged they will suffer combustion chamber over temps even though the engine temp is well within the bounds of "normal". A look into the air boxes can tell you if the thing has been abused and abuse of a 2 cycle is the correct way to drive a 4 stroke...lug it. 2's like3 thge r's and a 4 will wear itself out if reved.
1.700 rpm up hill at max load is LUGGING if you are into the throttle to keep it there. The process is to hit the hill in any gear and then back off the throttle 25% and that is the dooable speed throttle combo. You should be able to give it more throttle and have the bus pick up speed....even if slight. If it just growls louder and doesn't pick up you are in too tall a gear. On a hard pull you are supposed to back down gears till you can feel the governor holding back thge R's by cutting fuel. It is called "riding the gov." and it THE way you go up hill if it is any sort of pull.
A rad can't suffer the degradation of performance that you are experiencing at the given rate. ONE DAY GOOD AND THE NEXT BAD. Your thermostats CAN and WILL fail suddenly. In this case you might be suffering a degradation ovfthe operation. Sure it may open at 179 but it may do that and still not open fully. Soft Fail. They are too cheap and too easy to change to do almost anything else FIRST. Replace BOTH thermos.
The 92 has a thermostat in each head. One can start to fail softly and it will be masked by a temp indication that's only slightly high. This is where your gut comes in.
The temp you read at the front of the bus is for one head only. You have two heads and you need a gauge for each head. The right bank always runs a few degrees hotter cause it cools the aftercooler.
The alarm for over temp should sound at 205. There is a thermo that controls that. The auto shut down thermo should kick in at 210. Both of these are on one ban and as I said if that is the "cool" bank you will already have cracked the other head. The smart money is on installing a over temp and a auto shut down in the second head and just simply connecting them in parallel. The 92 heads crack at 213 and don't believe those stories about mirecles.
When going up hill and you are backing out of the throttle you should see the black smoke QUIT. Black smoke on a hill for more than a few seconds is very bad indication. Keep backing out and down shifting and let the gov do its job.
There is a mod to the 740 that allows you to force lock-up in first so you can use the jake while picking your way down switch backs at 10 MPH. It follows that you can force it out of lock. Given that the trans sheds its heat thru the rad it will increase heat from the trans to do so. Might be that the trans would contribute less than the lugging but the lugging will most certainly KILL the engine.
Get a no contact thermo gun and shoot both rads in and out and compare. Also shoot the rads all over and look for a cool spot. That is where it is plugged. You sound like you have a good system and you certainly "had" and I hope still have a good engine.
John