Engine/Transmission (1994 - 1998) Overflow valve again???

[drawson]

I replaced the overflow valve back in dec. with a bosch factory unit. After my travel to Calgary I started noticing the same types of problems I was having with the old overflow valve. The truck starts funny first thing in the AM. It starts but then barely run for just a secound then it's fine until the next morning. I pulled it and the spring is too short and bent. I straitened it and added both the small spacer washers off of the old overflow valve and the last three morning she's alright again.



I didn't have anyproblems up in Calgary, so the overflow spring did it's thing on my way home. I did do 680 miles towing my TT non stop. I was pushing it alittle coming home, but the coolant temp never got out of hand and I never exceeded 1300 deg EGTs.



All I can figure is the spring lost it's tension due to being hot for that long haul home.



I already tried making my own springs out of some gunsmith springs, before replacing my first overflow valve, none of my three tries held up.



Anyone have any ideas on how to keep this from happeneing again???

 

[illflem]

Dee, my feeling is high fuel temps on extended drives especially when the tank is low weakens the spring. I've seen up to 210° on the bottom of the tank. Fuel cooler or keep the tank over half full? Put the cooler on the return line, shouldn't take much. Sure would be nice to find a source for the 10¢ spring, it's probably is the cause of 95% of all valve failures.

 

[The patriot]

If/when I get a new overflow valve, I'll go to Wolff gunsprings and see what they can do. Theyre not too far from me.

BTW, I stretched my spring a bit too much... ... 37 psi at idle.

I gotta get around to pulling out a shim or two... ...

Eric

 

[drawson]

Eric I have a complete set of springs from Brownells and I was able to get one that was the right size but it lost tension way too fast.



Bill I think you are right about temp of the fuel and I was pushing it to get home and knew I had the range to make it w/o fueling. When I filled it after getting home it took 34. 8 gallons. I have never ran it that low before

 

[MDKram]

Dee, have you determined what the spring rate is? If not, we have a jig in our lab to very accurately determine this. What do you think about using a helical spring instead of a conical spring with the same mean spring rate? It seems the selection and availability of helical springs is much greater than that for conical springs. Just a thought.



Marc



Glad to here your trip home from Calgary was uneventful!