Couple of (different) heat related glitches

[Logical1]

I pay absurdly close attention to just about every part of my dime and have run into two funny little issues:

 

#1

I always warm my baby up first thing in the day. I usually cruze around the waterfront and just enjoy my Datto. My L18 always runs cool (around 160f) for average NW days. It burns very little oil & coolant over several months, However sometimes the thermostat does not kick in @ around 190f and the temp keeps climbing to 220f+ I Pull over and turn the engine off. After less than 1 minute I watch the temp roll back down and start her up and now everything is kosher. It only does this occasionally! My thermostat works fine, I keep it filled with proper coolant and have flushed the crap out of her several times. Only thing I can come up with is, cavitation in the water pump that prevents the hot water from reaching the thermostat and thus doesn't engage the radiator, ect, ect... ???

 

#2 I have a nice Mallory high flow fuel pump for carb's. It has never gone out on me (knock on wood) and works great! However, Lately I stop driving and take my kill-key out. Just out of the habit of checking things I check and feel the various components in my fuel system. I Have noticed that my main fuel pump is getting fairly hot! Not quite enough to burn you but damn close. I have it on a return line system and change my filters regularly. When on, The fuel flows nice and easy and I can see it swirling through my filter. Maybe I have just never noticed it before but is this normal for this big boy electric fuel pumps to get this warm? Here is what mine looks like:

 

 

[ggzilla]

Sounds like your thermostat is not fine (just mostly fine). But occasionally it doesn't open up when it should.

 

High power fuel pumps get hot. It sound normal to me.

[datzenmike]

1/ Cavitation only happens (if at all) at high RPMs so don't worry about that. The thermostat is on the outside of the head and there is a lot of distance between it and the hot water around the cylinders so in order for the thermostat to know how hot that water is there is a small fitting on the thermostat housing with a pipe going down to the lower rad return hose so water will circulate round and round past it. Without this connected the engine relies on convection for the heat to find it's way to the thermostat. This can take some time and the motor can get very hot before it opens. See if yours is there or the hose crimped.

 

Most L20B and a few L18 with air/con had the return line. It was to keep the fuel in the line after the pump circulating and not allow it to get hot. Constant cool fuel is always flowing past the carb. Any air bubbles from boiling gas will be returned to the tank. On the L20B there is a restriction in this line. A pin hole actually, very small. If there is a restriction, the electric pump will be able to get up to max pressure and will shit off. (and take a break) If there is no restriction it will be pumping full speed all the time. No wonder it gets hot. My 620 has a 720 electric pump and on turning the key there is a purring sound as it builds pressure. This quickly changes to a slower beat once the carb is primed. The restriction still allows some gas back to the tank and the pressure drops and the pump replaces it.

[Logical1]

Update: Fuel pump just shit the bed on the highway, luckily I have two pumps in my fuel system: one that pumps fuel to my surge tank, and the Mallory to pump to my engine. I kinked & taped the surge tank return line and the little walbro had enough pressure to push past the dead Mallory and get me home :)

[I'm BLUE]

Update: Fuel pump just shit the bed on the highway, luckily I have two pumps in my fuel system: one that pumps fuel to my surge tank, and the Mallory to pump to my engine. I kinked & taped the surge tank return line and the little walbro had enough pressure to push past the dead Mallory and get me home :)

 

awwwwwww that sucks :angry: ^^^

 

Glad you had a back-up plan in place ;)

 

How long did you have the Mallory for ? What Pressure running and was it regulated ?

 

:)

[Logical1]

I've had the Mallory for just under a year. I had it on a regulator @ 3psi for my SU's with a return line. The pump was a beast when it worked, and was the loudest damn fuel pump I have ever hear! It never seemed to turn off/down like Mike said when the optimum fuel pressure was reached and only started getting hot about a month ago. I have a very nice flowing fuel system with filters I change regularly, not sure why it crapped out. Possible manufacturer defect? I'm a electrical dork So I am going to pull it apart and check the brushes/bearings :)

[I'm BLUE]

Cool Man ! ^^^ I would prob take it apart to ,,, :lol:

 

 

I'm not sooooooo good with electrical ( but I good by just fine with basics ;) )

 

 

Great ,,, Update this ASAP ,,, You have me curious :huh:

 

 

Thanks Logical1 ! :)

[ggzilla]

What's the point? A stocky factory L18 fuel pumps flows enough the twin carbs. Also, single pump is more reliable than two.

[Logical1]

What's the point? A stocky factory L18 fuel pumps flows enough the twin carbs. Also, single pump is more reliable than two.

 

 

Whats the point? Under that rational, whats the point of any mod's away from stock? A stock L16 will move a 510 down the freeway, get good mileage, and run forever. although I don't see many stock dimes out there... I have a VERY custom fuel set-up because it was fun to design, fun to build, is completely original, and works well. That's my point. I had a piece of equipment go out and wanted to share the possible cause with others who could watch out for the same signs of trouble.

[ggzilla]

Fair enough.

[Logical1]

Took the beast apart:

 

 

Upon inspection there was lots of black debris/dust in the motor casing. The 'brushes' had plenty of material left on them and the copper contacts seemed to be in good shape. I couldn't find the exact cause of failure but it looked to me like the lower bearing had gotten loose and allowed the armature to rub on the magnets and create heat till it seized. I put it back together and tested her out, worked great but started generating heat rapidly. I could possibly re-build it but I'm thinking about trying another brand/style of pump for my main engine pump. Any suggestions for a good carb pressure pump with a high flow rate?

[I'm BLUE]

Thanks for posting that Logical1 :) ( this will help me in my future projects ,,, soon ! ,,, very nice pics too ! )

 

Contact Mallory to address the issue ,,, send them the pictures ,,, receipt of purchase ( copy ) and a very nice explanation of had happened ! ( that's what I would do ,,, worth a shot , and nothing to lose at this point ;) )

 

I personally just run the cheapy electric fuel pumps (typically) ,,, always with a regulator :lol: ( carter , etc... )

 

This is a little concerning that the pump wen't out so soon ? :unsure:

[ggzilla]

Looks like a wiper motor.

[hang_510]

Took the beast apart:

 

any suggestions for a good carb pressure pump with a high flow rate?

carter 4070