detroit cracks and cranks?

Sounds like typical '97 DDEC IV behavior to me...

 

from the look on pic it does have the pre heater.

 

this O ring is it where the preheater screws in ?

 

It's not the Bottom Collar, which also has a O-ring, which is different than the Top Collar O -ring.


It's right next to the drain valve and where the two coolant hoses go into the heater. It looks like a big thin nut, but it unscrews. One you unsrew it, there a O-ring attached to it.

 

o.k. now I'm really confused I know that I do have the preheater. it is on when key is in on position. it is 12 volt. no coolant hoses at all. I have the davco 380 I have small bubbles visible in my davco, thinking it is a pick up tube cracked in tank, but hoping it could be something in the davco, the top collar & bottom collar -o- ring are fine as replaced every filter change. the bottom drain valve also replaced.

I replaced the ball & spring in the check valve cause someone (not to mention my name) let a piece of foil from a anti gel bottle get into tank & caused a drain back problem. just wondering if there is another o ring somewhere that I have not changed already.

 

Post a picture of the underside of your Davco, (like if was turned bottom up) so I can see a clear picture of what it looks like.

I have a Davco 385, so it might be configured differently than yours.

 

If you suspect that the Davco has an issue, just bypass it with a clear tube to check it. If you still get bubbles in the tube, the air is coming in before the Davco. Or you could take off the line from the tanks to the Davco and run it from a bucket of fuel to see if the air is still there. That'd at least give you a direction to go.