| OT - Looking for help/advice with low and hi pressure issues [message #258692] |
Wed, 13 August 2014 10:35  |
Ultravan Owners
Messages: 443
Registered: March 2013
Karma:
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Senior Member |
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Hello everyone,
Most of you know at this time I still don't have a GMC.
But I do have a 455 setup in the back of a motorhome called an Ultravan.
This coach sat for many years. I spent part of May, all of June, getting the mechanical in good shape.
And because it is not a GMC I did the OT - title...
It runs well and does not overheat, when running in the driveway, even on fast idle.
However, it has an overheating problem on the highway.
Ultravans with water pumpers have always been known for overheating issues. The PO purchased it from a dealer. He dorve by it and turned around to see it. It was so different he just had to have it. Sadly he passed away just before I picked it up in July 2013. I spoke with his wife last week. I call her from time to time since we started working out the deal to buy this coach back in the fall of 2012. She has become a dear friend to Marie and I. She is now 84 and I told her that it is running well but it overheats on the highway. It must have brought back memories. She went on to tell me they only used it a couple of times locally due to it overheating on them when they got it.
I need to know what to look for and how to tell if it is low or hi pressure moving around behind the engine along with the fornt and back of the radiator.
The power plant sits under the bed in the back of the coach and the radiator is about two and half to three feet behind the engine at the rear of the coach.
FYI - It has a new Flex-a-Lite aluminum radiator with a 3,300 cfm electric fan. I rebuilt the carb, gave it a tune up - less sparkplug wires - until I can find the best (correct) angle boots to work in the tight fit area. I have purchased - but not yet installed a high volume water pump.
Vacuum gauge reads were on the higher side of the good reading area. (Sorry I don't recall the reading)
All I know is that it was very steady and good.
Also I don't see any signs at this time of a head gasket problem.
I need to get air flow through the radiator while on the highway.
I know I'm delaing with low and/or hi pressure area in front of the radiator and around the engine.
I just don't have a clue how to diagnose which it is and how to correct the issue.
It has a large ugly fresh air scoop on the side of the coach. However, I'm not so sure the air is going in it and not trying to get out of it and the engine compartment.
Any help would be appreciated.
Sincerely, Tony
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