Racor question/explanation?

In Memory Walter K · Post by **In Memory Walter K** » Jun 11th, '11, 17:27

For the last two weekends I have had my starboard engine start up immediately as usual, but in about a minute or two, shuts down seemingly from lack of fuel. I then go through the bleeding/priming process, and get it started again. The rest of the day goes normally. In the past (2-3 years ago) I had a similar problem that drove me nuts until I discovered a hairline crack in the base of the bowl. Replaced the bowl and the problem never showed up again...till now. In a telephone conversation with my mechanic, he suggested I close the incoming fuel line valve on that Racor when I shut down and let it sit for the next week, then open it just before starting. Today I did that and the engine ran without the previous shutdown. He felt the fuel was slowly running back to the tank. I know that there is a check valve in the Racor that probably needs rebuilding but my mechanic says he's been having varying degrees of success which he attributes to the newer Diesel fuels affecting the seating materials in the Racor. He recommends a metal to metal check valve installed on the fuel line, preferably as close to the tank as possible. My question is: if the gaskets on the Racor are tight and there are no air leaks anywhere on the line, is it pure and simple gravity at work combined with the air in the fuel tank? I would think if everything is tight, the fuel would stay put but if the fuel does drip down and semi empties the fuel reservoir on the Racor, where does the air in the top of the Racor come from? A simple answer I am sure, and I'd just like to understand the solution better.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Jun 11th, '11, 18:52

Walt, I've never trusted the check valves - I'd go thrugh the Racor from top to bottom again looking for air leaks, especially in the bowl, its drain, and the small o-ring around the T-handle. A tight fuel system should not drain back in a week or so, but a leaky one will drain back fast. Our 6Bs air lock in a heartbeat and won't shrug off even a little air.

My last bout with this problem also turned out to be the bowl - cracked around the threads at the bottom where the drain screws in.

UV

Bruce · Post by **Bruce** » Jun 11th, '11, 23:05

I wouldn't add a check valve either. The 6bt's have enough fuel pulsations from the primary pump and the extra pull for opening a check valve could possibly shorten the pump diaphrams life.

Its easy enough to get a rebuild kit and install a new gasket and ball.

While fuels have less sulfer content, I haven't seen anything that would affect plastic or rubber parts. If someone has seen this issue let us know the details on wether it could be a regional thing with winter blends possibly.

Like Vic said, the other issues are lid and t handles o rings along with the bowl.

Harry Babb · Post by **Harry Babb** » Jun 12th, '11, 06:55

Bruce

Isn't there a check valve incorporated into the return line fitting on the side of the Nippo injector pumps?

hb

Joef · Post by **Joef** » Jun 12th, '11, 07:55

Walt...i dealt with the same crazy thing for about 3 seasons with my Cat 3208T engines ...though easier to restart after stalling out, it still was a major pain. While i did have other issues...i did find leaks in my racors. My solution was to replace them with those "double-double" fleetguard filters that Tony Athens sells. Basically truck style filter heads wtih appropriate filter / water seperator spin-on style filters on them. There is only one thing to leaks on them - the giant big o-ring on the top of the spin-on and its really not likely. As a Six-Sigma quality weenie for GE we always like the idea of eliminating Defect Possibilities. ...with those filters you eliminate a bunch of seals, plastic bowls and check-valves. ...of course, they've (racor) been around for one gazillion years and i'm sure a simple rebuild would fix your issues for a long time too. The other thing i like to throw around at work is the UV theorem that the "enemy of good is better".

Joe

Bruce · Post by **Bruce** » Jun 12th, '11, 10:25

Harry,
I believe so but since retiring my mind has turned to mush.

Not being mentaly challenged everyday, er let me put that another way, my mind not being, um.... stimulated. Thats the word I was looking for. Not being mentaly STIMULATED everyday, the memory doors in the minds mansion are closing. And if I wait much longer, the mansions gonna be forclosed on. Now I know why my dad up till the day he died never "retired".

-------

The solution to general maintenance tasks can be replacing those components with those that you remove and throw away.

But I'm not sure how many dock jockies have been out in a rough seas where boat contol is imperative and a bad fuel issue creeps up.

I for one have many times in shuttling boats from point a to b.

I've had to deal with racor types and spin on's.

Sorry but in a rought sea, I'll stick with the racors to get the engine or engines back up the fastest.

Capt.Frank · Post by **Capt.Frank** » Jun 12th, '11, 12:06

Walter, on my 3208 NA I had some corrison on the top of the racor. The o-ring sealed, but it would leak under demand. That engine would start and shut down, Air leaking in around the lid where the T-handle is. my .02

In Memory Walter K · Post by **In Memory Walter K** » Jun 12th, '11, 13:56

If all is properly sealed, can it still drip down back to the tank to create an air space in the Racor? I kind of liken this to lower unit oil in an outboard. You can unscrew the lower drain screw, but it won't run out until you crack the top screw.

In Memory of Vicroy · Post by **In Memory of Vicroy** » Jun 12th, '11, 15:26

Not sure if it would over a week....unless there is no check valve or equivalent in the fuel return line, and the return line dumps in the top of the tank vs. having a tube down into the tank similar to the fuel pickup.

On mine, the fuel return just dumps in the top of the tank and I've let her sit for a year with no fuel drain-down. I'd continue to suspect an air leak somewhere between the fuel shut-off and the injector pump, with the Racor being the prime suspect.

UV

CamB25 · Post by **CamB25** » Jun 13th, '11, 08:25

Walt,

Fluids will always try to move towards equilibrium. Assuming that the tank is vented, no check valves and the upstream system is not 100% sealed, the fluid will flow as the ratio of the column heights. Tank low - flow to tank. Engine low - flow to engine. The air may be coming from the engine side as the pressure drops to zero and flow from Racor displaces the air in the system. I'm assuming the your Racor is the high point in the system. This might explain why it starts and runs until the injector pump encounters the air.

Caveat: I have close to zero marine diesel experiene, but we used to run into similar drainback issues on railcars if we let the engines sit for more than a week or so. First step to start the Cats was to work the primer lever on the fuel pump to displace all the air in the system caused by drainback to the tank over time.

Cam

CaptPatrick · Post by **CaptPatrick** » Jun 13th, '11, 09:38

The most simplistic solution is to close the ball cock valves at the exit point on the fuel supply manifold after the engines are shut down... Open them just prior to startup. Doing the same on the returns might help also.

The fuel is trapped in the line and tank volume and venting become non-issues.

Rawleigh · Post by **Rawleigh** » Jun 13th, '11, 10:18

Walter: It has to get air in somewhere to leak down. As usual Capt. Pat has the KISS idea!!

Bruce · Post by **Bruce** » Jun 13th, '11, 19:28

Shutting the valves is a kiss idea and a short term solution.

But finding and curing the issue should be done. I never saw a small problem not turn into a larger one when ignored.

bertram31.com

Racor question/explanation?

Racor question/explanation?

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