Thermostat behavior differences (6v92)

[Brian Diehl]

I'm in the middle of replacing my coolant and thermostats.  I thought I had 160 degree stats, but turns out I had 180 in already.  I decided to test the old right next the new in a pot of water.  Both start opening almost dead nuts on 180 degrees.  However, by 190 the new thermostat was open almost an entire 1/8" more than the old thermostats.  In addition, one of the old thermostats was opening crooked.  I suspect that is not good behavior!  The new thermostats I got from Luke @ US Coach have a slightly different design than the old ones.  The new ones have the spring and retaining bracket below the part of the housing that is imobolized in the bus.  This allows the thermostat to open truer as it only slides down the center shaft.

On a side note, I had to replace the fuel cross over hose that goes from the left to the right heads.  The old hose was falling apart down to the internal steel jacket!  Turns out the part has the equivalent of power steering hose ends on it and can't be made up at any of the truck supply places I went to.  However, NAPA did have the fittings and the hose and was able to make a direct replacement for me!  Now all I have to do is figure out how to reprime this beast once the coolant hoses I need to replace have been replaced and the new coolant put in.

Ah, the fun of these old diesels and good ole Napa!

[ChuckMC8]

Brian, its a good time to add an electric primer pump for the fuel......12v pump from auto zone and a few home depo fittings and goodbye to priming woes! Probably do all for $40 or less...click on my profile and you can see my setup. It works great..I put new fuel filters on dry and then turn on the pump to fill them and prime the system. HTH Chuck

[TomC]

What Chuck said about putting in a primer pump is a good idea. And---installing the fuel filters dry is always the safest way since there is always the chance of getting a small piece of dirt on the wrong side of the filter when filling them up from a can.  The electric pump can at times of mechanical failure get you out of a bind.  It is good to stay with the 180 thermostats for best efficiency.  Good Luck, TomC

[Brian Diehl]

Thanks guys.  I've got a 24v pump Napa is getting in for me today.  I'll pick it up tonight after work and hopefully have it plumbed in by early next week for my first restart after all this work.

[gumpy]

Hope you ordered the high pressure pump from napa, and not the lower pressure pump. It should be about 13 psi, and not more than about 20 psi.  Their small one just didn't have enough push to work well. BTDT.

Also, post some photos of the two different thermostats, if you can. Would like to compare the ones I have waiting to install with yours.

[Brian Diehl]

Here are two side by side pictures comparing the old with the new.  The new one is still silver (on the right side of the pictures).

[Stan]

Chuck: My understanding of the DD fuel system is that the fuel first goes through the 'strainer' then through the fuel pump and then through the 'filter' which feeds the heads.

The fuel pump is a positive displacement pump that you cannot push fuel through unless it is turning or the pump is severely worn.  Your installation picture looks like the auxillary pump is on the inlet line to the strainer. How do you get fuel into the filter after the pump?  Do you crank the engine while the auxilllary pump is running?

I always replaced the engine fuel pump when I bought a bus and I could not pump fuel with an auxillary pump through the system. The auxillary pump was added after the engine pump was replaced so I have no experience with an older pump. What is the secret?

[ChuckMC8]

 Yes, I Just turn on the electric fuel pump and it makes a rapid pulsation sound, when the sound slows down to a cluck-cluck (;-0 then I start the engine and off she goes. I run it for a few minutes and turn off the electric pump and turn the valve and move along. (So, yes I crank with the aux pump running)
I never thought about how/why it worked.....it's my "modus operandi"
But probably the fuel pump worn... I'll see how it works with my new engine.....If I get it installed!

[Busted Knuckle]

Chuck you'll get it installed and then it's time for RALLY'ING ! LOL! Opps! Let's modify this an start at the Deleware Rally! LOL!

Bruce & Nicks Gig Deleware Sept 22nd-24th
Eagles Bash Branson, MO Oct 2nd-5th
Dallas & Cats Shindig Timmonsville, SC Oct 5th-8th
Christy's Jersey Round Up Carthage, MO Oct 13th-15th
TN Fall Bus Bash @ Knuckle's Union City, TN Oct 26th-31st
PLEASE do not wait till the last minute to sign up or worse yet, just plan on dropping in.  All rallies take a lot of planning .  We must know how many folks are coming so we can plan the activities.  I am sure we plan for a few extra, but if we are overwhelmed with folks we did not plan for, that becomes unfair to everybody.  End of soap box!
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Get those registrations into Bruce/Nick, Byron, Dallas & Cat, Christy, & Me and look at all the fun you'll have going to Deleware to Branson, MO to Timmonsville, SC, to Carthage MO, and then here to Union City, TN for an excellent extended month long adventure of camping and commodere! BK!