| 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: 0
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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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| Re: OT - Looking for help/advice with low and hi pressure issues [message #258699 is a reply to message #258692] |
Wed, 13 August 2014 11:11  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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I can't answer your questions exactly but you need to know is the radiator itself hot like it isn't cooling the coolant? A laser temperature thermometer will tell you this (harbor freight). Since the radiator is off to the side you can't use an engine driven clutch fan. A couple of months ago I fixed a friends firebird that was overheating. He had a fancy electric fan put on it in place of the standard fan when they added an a/c system. Three shops and $4000 later it still ran hot. I took the electric fan off as it barely moved air put a stock shroud and heavy duty clutch fan on it big difference no more cooling problem. I could have found an electric fan that would have moved a lot more air but then I would have had to replace the alternator with a larger one and increase wire sizes. If your radiator isn't cooling you should look into getting the most powerful electric fan (s) you can buy. I heard ford t bird fans move a lot of air? You will possibly need a larger alternator 100 amp or more as big fans draw a lot of amps. Your radiator may or may not be large enough. Is the water pump moving enough water? If the radiator isn't hot that could be a problem but if the radiator is really hot it is most likely ok. I you need to move more coolant flowkool makes a nice high volume water pump for the Olds engine. Are you using a Robert shaw style thermostat? Just a few thoughts I think you will find your problem is in this area.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] OT - Looking for help/advice with low and hi pressureissues [message #258712 is a reply to message #258692] |
Wed, 13 August 2014 11:58 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Photos?
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Tony
Sent: Wednesday, August 13, 2014 10:37 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] OT - Looking for help/advice with low and hi pressureissues
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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Unsubscribe or Change List Options:
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: OT - Looking for help/advice with low and hi pressure issues [message #258713 is a reply to message #258692] |
Wed, 13 August 2014 12:08 |
Ultravan Owners
Messages: 443
Registered: March 2013
Karma: 0
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Senior Member |
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Roy,
The radiator is behind the engine, not the side. And because it is behind the engine I cannot run the fan on the WP. Also I need to be sure that I have air flow while driving at highway speeds.
Hal,
The elecetric fan is pulling. FYI - I did try both ways. NO real change that I could see/tell.
Tony (Ontario Canada)
Marie and I are blessed to have had a 2nd chance to buy our farm.
Still hoping and more importantly praying to be able to build a garage.
Our 1970 Ultravan #520 has an Olds Toronado 455 in back.
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| Re: OT - Looking for help/advice with low and hi pressure issues [message #258716 is a reply to message #258713] |
Wed, 13 August 2014 12:44 |
George B.
Messages: 213
Registered: February 2012
Karma: 1
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Senior Member |
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Is there shrouding between the fan and the radiator? In your configuration without one to funnel the air flow the fan may be ineffective. If the fan is just near the radiator without a shroud it may just be recirculating the free air around the fan and not pulling or pushing air flow through the radiator.
Another thing to look at is your lower radiator hose. Sometimes if that hose is soft and pliable it may collapse at higher RPM due to the suction of the water pump. The way you say your radiator is mounted I suspect you may have a longer than normal hose.
George Butts
Las Vegas Nevada
73 "Custom 26' Q" & 76 23' Birchaven
71 Honda 600 Coupe & 01 Tracker Toads
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| Re: OT - Looking for help/advice with low and hi pressure issues [message #258729 is a reply to message #258692] |
Wed, 13 August 2014 14:36 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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You obviously have the symptoms of insufficient heat exchange (cooling). It looks like you have approached the problem in the traditional way but have not found the component that will fix your problem.
So,
Is it a poorly sized or restricted radiator?
Is it poor air flow through the radiator?
Is it poor coolant flow?
Is it a thermostat failing to fully open?
Is is poor heat exchange between between the engine and the coolant?
Is the engine generating too much heat? (Ignition timing and advance) (Where are exhaust components in relation to the radiator?)
Those are what I think you are trying to determine.
Since it primarily fails at highway speeds, it is going to be difficult to point a heat gun thermometer at a component and see what it's temperature is at 45 mph. If you take a look at a GMC radiator you will see it is huge and it barely does the job in some cases. It also has a BIG fan for boosting air flow a low speeds. I do not know what yours look like.
I do not have the solution to your problem but I suggest that you may start by attacking the possible problem areas listed above. I would check the ignition timing and the proper operation of the vacuum and centrifugal advance just to eliminate those as an issue. I'm thinking that adding one or more temperature sensors might help locate the problem. I would start by installing one in the lower radiator hose. That will tell you whether the radiator is cooling the coolant enough before returning it to the engine.
Based on readings of the new sensor(s), I think you are probably going to be looking at airflow issues and / or radiator sizing. Normally you should not have to use any radiator fan at highway speeds so I would be concentrating on air flow issues. I believe yours is a pusher type installation with a rear mounted radiator like a bus. If this is the case, you might need a BIG engine driven or electric fan to keep air flow going through a large radiator if it is not in the air flow path. Maybe some additional ram air ducting towards the radiator might help.
Pardon my rambling. These are just some ideas.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: OT - Looking for help/advice with low and hi pressure issues [message #258733 is a reply to message #258718] |
Wed, 13 August 2014 14:54 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Tony did you measure the voltage at the fan motor when it is operating? You will need it to be around 14 volts so large wire is needed. How many amps is it drawing ? The big ford and Lincoln fans pull around 60 amps to move 5000 cfm you may need to go this route more amps should mean more cfm that fan that you have may be falling short. Draw through should move more air then pushing.
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Wed, 13 August 2014 14:55] Report message to a moderator |
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| Re: OT - Looking for help/advice with low and hi pressure issues [message #258854 is a reply to message #258692] |
Thu, 14 August 2014 23:01 |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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Senior Member |
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Tony,
Looking at the pictures, I think the radiator is subjected an over abundance of engine heated air, and a shortage of scooped ambient air.
The hotter the air temp to the radiator, and the hotter the water needs to become before any thermo exchange can occur.
Deflecting (from the radiator) the engine heated air may do the trick.And/or modify the scoop to be variable opening, like cowling vents on radial engine. Scooping more air at higher speeds.
Just food for thought.
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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| Re: OT - Looking for help/advice with low and hi pressure issues [message #258890 is a reply to message #258718] |
Fri, 15 August 2014 10:01 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Ultravan Owners wrote on Wed, 13 August 2014 13:55Rob,
You just want something (pictures) to look at.. 
Looking at the engine from inside the coach.
There is a step to help you get into the bed above the engine and the step is just in front of the water pump.
<photos deleted>
The transmission and all hte space behind it before the radiator.
The old and new radiator.
This is the Flex-a-Lite Radiator I used. It comes with the 3,300cfm electric fan and shroud you see.
Here I have installed the radiator.
I'm standing behind the coach looking towards the engine.
I'm working on a shroud idea to help force cool air into the radiator at highway speeds.
In this picture you can see the large air scoop someone installed.
For my first highway test I left it on. I removed it before my second highway test.
It did seem to allow me to go a little farther - but not much father before it overheated.
Tony,
I am not an aero-engineer, but as a marine engineer and naval architect, I had to learn a lot about how water flows.
After looking at your pictures and letting it sink in, I think I may see at least part of the problem.
It all comes from memories of trying to do "scoop induction" for the cooling water for a high powered high speed steam ship.
On our early cut, we got something wrong and it didn't work at all. It turned out the the flow coming around the shipside actually blocked the outflow from the condenser.
You may have the same thing happening here. The body pushed the air open and as it drives into the hole, that air comes back against the body and slides along it until the body tries to pull out of the hole. Unfortunately for you, this makes a solid sheet coming off the roof that can act as a cover for the radiator's discharge.
Cheap and dirty trial for a proof of the above. Get something like 2"square syrofoam and duck tape it to the body as close to the air outlet as you can around the three sides. If I am correct, even this little bit may make a big difference. If it does get you something, but not enough, you may have to go bigger. Remember the Porshe Whale Tails? I was told that they actually helped cooling as much as they improved the handling.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] OT - Looking for help/advice with low and hi pressure issues [message #258909 is a reply to message #258890] |
Fri, 15 August 2014 11:25 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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No pix
FREE WIFI @ Mickey D
On Aug 15, 2014, at 8:01 AM, Matt Colie wrote:
> Ultravan Owners wrote on Wed, 13 August 2014 13:55
>> Rob,
>>
>> You just want something (pictures) to look at.. :d
>>
>> Looking at the engine from inside the coach.
>> There is a step to help you get into the bed above the engine and the step is just in front of the water pump.
>>
>>
>> The transmission and all hte space behind it before the radiator.
>>
>> The old and new radiator.
>>
>> This is the Flex-a-Lite Radiator I used. It comes with the 3,300cfm electric fan and shroud you see.
>>
>> Here I have installed the radiator.
>>
>> I'm standing behind the coach looking towards the engine.
>> I'm working on a shroud idea to help force cool air into the radiator at highway speeds.
>>
>> In this picture you can see the large air scoop someone installed.
>> For my first highway test I left it on. I removed it before my second highway test.
>> It did seem to allow me to go a little farther - but not much father before it overheated.
>
> Tony,
>
> I am not an aero-engineer, but as a marine engineer and naval architect, I had to learn a lot about how water flows.
> After looking at your pictures and letting it sink in, I think I may see at least part of the problem.
> It all comes from memories of trying to do "scoop induction" for the cooling water for a high powered high speed steam ship.
> On our early cut, we got something wrong and it didn't work at all. It turned out the the flow coming around the shipside actually blocked the
> outflow from the condenser.
>
> You may have the same thing happening here. The body pushed the air open and as it drives into the hole, that air comes back against the body and
> slides along it until the body tries to pull out of the hole. Unfortunately for you, this makes a solid sheet coming off the roof that can act as a
> cover for the radiator's discharge.
>
> Cheap and dirty trial for a proof of the above. Get something like 2"square syrofoam and duck tape it to the body as close to the air outlet as you
> can around the three sides. If I am correct, even this little bit may make a big difference. If it does get you something, but not enough, you may
> have to go bigger. Remember the Porshe Whale Tails? I was told that they actually helped cooling as much as they improved the handling.
>
> Matt
> --
> Matt & Mary Colie - Members GMCMI, GMCES
> '73 Glacier 23 - Still Loving the Applied Rear Brake Control Arms
> SE Michigan - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] OT - Looking for help/advice with low and hi pressureissues [message #258921 is a reply to message #258909] |
Fri, 15 August 2014 12:48 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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They were in the message I saw, however, when I looked at them I still couldn't understand the air flow path, sorry
Regards,
Rob M.
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Mr.erf
Sent: Friday, August 15, 2014 11:25 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] OT - Looking for help/advice with low and hi pressureissues
No pix
FREE WIFI @ Mickey D
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] OT - Looking for help/advice with low and hi pressureissues [message #258953 is a reply to message #258921] |
Fri, 15 August 2014 17:58 |
Jim Rountree
Messages: 47
Registered: July 2010
Location: San Antonio, TX
Karma: 0
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Member |
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When checking air flow on airplanes we used a very simple method. We cut yarn into 10 inch strips and duct taped them all over the area in question. Drive the van at a steady speed and make movies of the yarn action. You learn a lot about air flow patterns. You could do the both externally and internally. Simple and quick. Make runs different speeds. If you want pressure info use a manometer and place home made pitot tubes in the area or air stream.
Rear engine installation are difficult to cool. look at busses that have huge side radiators and big hydraulic driven fans drawing air directly from the outside.
Good luck
Jim Rountree
San Antonio,TX
76 PB,
76 Royale RB
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| Re: OT - Looking for help/advice with low and hi pressure issues [message #259095 is a reply to message #258692] |
Sun, 17 August 2014 09:04 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Senior Member |
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I suspect your problem is compounded by having heated engine air blowing through the radiator. The heat has to go somewhere and the radiator is about the only exit.
Have you considered some of the super coolant products like "Engine Ice"? There are a bunch of things like that that the hot rod boys use that are much more efficient than traditional coolant/antifreeze.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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