(Cold Start) CHT question.. (mine is a '74 LJET)

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steve_1125
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(Cold Start) CHT question.. (mine is a '74 LJET)

Post by steve_1125 » Mon Nov 04, 2013 7:21 pm

Hello All, I am including a reply Ray gave to Dub earlier this year regarding his DJet and cold start (CHT question...) I have a '74 LJet wagon and the idling or lack thereof at red lights or stationery has become quite frustrating. Questions, Ray, does your description below include LJet (with respect to sensors and cold start parts)? Per Clymers it appears all type 4s had a cold start valve and thermostat (a Clymers diagram also describes a fuel injection system but references only 1971-73 with a cold start jet, electro magnetic valve and temperature switch). Also, when you refer to $30 sensors or CHT, below, is that synonymous with the cold start valve? Any feedback would be appreciated and I hope this is clear :) Thanks, Steve
p.s. I can e-mail the specific texts and diagrams from my Clymer Publications VW 411 and 412 Service Repair Handbook if that would help



raygreenwood wrote:
90 is a bit low for cold weather warmed up. I would expect about 150 ohms at that temp. typcially with age these sensors die. They are about $30 and available.

The problem you are dealing with is a slightly rich or lean baseline fuel mixture. Get your CHT replaced, check your fuel pressure and make sure its stable at 28-30 psi.....and carefully adjust your valves, set your timing and clean and oil all parts in teh distributor.

Then carefully clean every connector in the system. One dirtly or slightly loose connectpor means resistance. Resistance means fuel mixture change.

Make sure you have no vacuum leaks and that your AAR is closing smoothly. Check back and we can go from there. Ray

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Piledriver
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Re: (Cold Start) CHT question.. (mine is a '74 LJET)

Post by Piledriver » Mon Nov 04, 2013 8:33 pm

~Everything relies on the CHT sensor being sane, which is what he is referring to.

It screws onto a boss on the 3/4 head (from memory) unless someone assembled he engine with the head with the boss on the wrong side, which is very easy to do...

Most often the grounds under the plenum are gross... replacing the push-ons with loops for an 8mm bolt does wonders.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

steve_1125
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Re: (Cold Start) CHT question.. (mine is a '74 LJET)

Post by steve_1125 » Wed Nov 06, 2013 5:23 pm

Thank you for the response Piledriver! Is this sensor the correct one for my '74? It says it is but just wanted input here, would be appreciated!

http://www.busdepot.com/0280130012

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Piledriver
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Re: (Cold Start) CHT question.. (mine is a '74 LJET)

Post by Piledriver » Wed Nov 06, 2013 6:01 pm

Yep, DJet and LJet take same CHT sensor.

For that price I'd buy two and save on shipping.

I'm somewhat dubious of it's provenance at $17, even if from Bus Depot, BOSCH is outsourcing a lot of it's parts to ex-soviet bloc countries and even China.

NOS would be preferred, lacking that, carry a spare.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

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