Date:         Fri, 7 Sep 2007 08:16:02 -0400
Reply-To:     Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject:      Re: Overheating (everything but the engine)-Vapor Lock
Comments: To: md03@XOCHI.COM
In-Reply-To:  <A58D95E1-04AE-40D3-98AD-5D025F918E22@XOCHI.COM>
Content-Type: text/plain; format=flowed

Actually, on  a fuel injected engine, vapor lock does not occur from the
fuel boiling in the fuel lines on the pressure side of the system. The fuel
does pick up heat while circulating through the system and eventyaully
raises the fuel temperature and vapor pressure of the fuel in the tank. The
actuall vaporization happens at the inlet (suction side) to the pump. Any
restriction before the pump such as a fitler or a clogged tank outlet makes
things worse. The pump cavatates and this interputs the flow and system
pressure. Also, if the vapor recovery system in the tank is not holding
pressure the fuel will evaporate faster. It is normal for the tank to vent
or release when the cap is opened. This is why VW went to a lorger tank
outlet and eliminated the filter before the pump. It is also why many
manufacturers put the pump in the tank or use a transfer pump to feed the
main pump.

Dennis


>From: Michael Diehr <md03@XOCHI.COM>
>Reply-To: Michael Diehr <md03@XOCHI.COM>
>To: vanagon@GERRY.VANAGON.COM
>Subject: Re: Overheating (everything but the engine)
>Date: Thu, 6 Sep 2007 16:46:03 -0700
>
>On Sep 5, 2007, at 2:18 PM, joel walker wrote:
>
>>>Issue 1:  However, when we were in the stop & go traffic, eventually
>>>something started to overheat.  The symptoms were a major loss of
>>>power, and dying at idle.   Let the van cool down for about 45
>>>minutes and it recovered completely.
>>>My theory is that some electronics were overheating, rather than the
>>
>>could also be vapor locking. i had this happen to me in a brand new
>>86 in colorado springs in rush hour traffic!! :( it was either that
>>or bad gas. and since vw came out with a recall about the problem,
>>i figure it was vapor lock. ;)
>>
>>what happens, in case you don't know, is that the gas in the hoses
>>on top of the engine starts boiling, and that means squirting not
>>just gas but gas and air. also messes up the fuel pressure. so the
>>engine runs really crappy. let the engine cool, and all is back to
>>normal.
>>
>>if it is vapor lock, how to fix? extra thermal protection/blanket/
>>tape around all the fuel hoses on top of the engine.
>>in the recall, they replaced all the hoses and the fuel tank (said
>>they changed the angle or something of the pickup line for the fuel
>>pump). me, personally, i don't think they changed the tank ... just
>>took the gauge sender off and mucked around down in there. cause
>>they messed up the sender and had to fix it again.
>>
>>anyway, think back to the altitude, too ... higher elevations bring
>>on the vapor lock quicker. :(
>>
>
>Interesting -- I hadn't thought about vapor lock as a possibility.
>I wonder if there's an easy way to diagnose vapor lock vs.
>electronics malfunction?     I suppose I could take a heat gun to my
>ECU and ignition control and see what happens :D
>
>
>>>Issue 2:  Also, the interior of the van was getting a ton of heat
>>>coming up through the floorboards, and through the passenger side
>>>seat pedestal.  Looking at the underside of the van, it looks like it
>>>has naked (uninsulated) rubber coolant hoses plus the exhaust from
>>>the radiator both directly next to the (uninsulated) firewall.  No
>>>wonder it gets hot in the cab!
>>
>>there used to be a kit from the dealer, with extra insulation
>>panels to go up under the bus, to fix that. you might want to check
>>around and just add some stick-on aluminum-skinned stuff on your
>>own in those areas. i think the bentley book says something about
>>the kit in the cooling system area. or the front heater area.
>
>Would you put that on the outside or inside of the van?  It looks
>like there's plenty of room on the outside, though I'd be worried
>about trapping dirt or water...
>
>
>>>3. Is the AC shutdown w/R134 due to overpressure (I've heard that
>>>R134 runs w/higher pressure).  Can I change out any parts, or do I
>>>need to go back to R12 or try freeze12 or something?
>>
>>might be the higher heat got into the a/c system and 'vapor locked'
>>it as well. and the compressor WILL shut off with overpressure.
>>which would not be unlikely in that heat ....
>>i don't think there's any parts you can change out, but thermal
>>wrap tape around all the hoses wouldn't hurt ... would keep the
>>external/outside heat from getting into the system as much.
>
>I was considering using regular plumbing pipe insulators, but those
>may melt if they get too hot... what would be a better insulating
>wrap for automotive use?