Fuel Tank Leak Question

[TruChaos]

Since I purchased my Jinma 284 in 2004, it has had significant fuel tank leak if I fill it above 3/4 full. Fuel pours out on the ground and all over the place. Of course when it leaks, fuel is all over the top of the tank so I don't know where it's coming from. Common sense dictates the most likely culprit is the fuel sender seal. I tightened the screws but I still have the same leak.

Does anyone know of a known problem with fuel sender leaks? I can see the rubber seal between the sending unit and tank, so I know it's there. All the screws are in their holes and tight.

I'm going to take it apart and put some sealer on the seal and around the base of the screws. Are the screws supposed to have rubber washers?

I also realize that it's possible there is leak at the point where the fuel filler neck connects to the tank.

Any recommendations or insight?

 

[Rich Waugh]

Remove the tank from the tractor and visually inspect it first. Look for signs of dirt collecting - that's usually where the leak is. If you can't locate it visually then apply a bit of air pressure to it and listen for a leak.

If you find that the leak is a bad seam, take it to a radiator shop for repair unless you know how to do it yourself. If it is the fuel level sender cut a new gasket from rubber sheet and re-install it. There should be no need for rubber washers on the screws if the gasket fits correctly.

 

[greg_g]

On mine, the sending unit gasket was that cheap cork crap, almost like paper. If/when a proper seal is not maintained, it gets wet and pretty much turns to mush. Yours might look like rubber simply cuz it's wet and deteriorating. I didn't have to remove my tank, but I did have to use some imagination with the tools. I ended up using a screwdriver tip on a 1/4" ratchet. That got the screws out so I could take the sending unit out and clean off the gooey mess that used to be the gasket. I then used the sending unit as a template, and cut my own gasket out of NAPA bulk stock appropriate for use with diesel fuel. Right up to the day I got rid of the tractor, never leaked like that again.

//greg//

 

[TruChaos]

I'm going to take it apart tomorrow. Now I'm curious about the gasket. I really, really don't want to remove the body. Disconnecting and reconnecting all that wiring and realigning the hood with the latch is not something I'm looking forward to.

I bought replacement screws with hex heads so I can snug them up with a 1/4 ratchet. If needed, I'd like to remove the old gasket and replace it with an RTV fuel resistant sealer.

Hopefully, that will fix it. It sure would be nice to actually have a full tank for once.

 

[greg_g]

Not sure what "all those wires" and "realigning the hood" means. If I recall, there are only three wires, and I did mine without removing the hood. I just fixed a light source so that it would illuminate that spot under the cowl, then went at it with screwdriver tips on the little ratchet.

And if you plan to replace the original machine screws with self-tapping sheet metal screws, you might end up making things worse. I had no problem re-using the original screws either. They were flat heads, which slowed things down a bit. But the leak is related to the rotten OE gasket - not to the OE machine screws.

I'm no fan of gasket-inna-tube either. In some circumstances I find it necessary to use it in conjunction with a conventional gasket, or to slow down a leak while I find the proper gasket. But I never use it as a permanent substitute for a proper gasket. Different strokes.

//greg//

 

[Rich Waugh]

Greg's method of removing the sender will work jut fine - I had to do it on my 304 to fix a broken wire in the sender. I have a set of gunsmithing screwdriver tips with 1/4" hex shanks that worked just dandy to get in there and remove the screws. Like Greg cautioned, do not replace the machine screws with self-tapping screws - use the OEM screws or direct replacements in the proper metric thread.

Like Greg, I don't use tube goop for gaskets unless there is absolutely nothing else that will work. It only takes about a minute to cut that gasket from proper gasket material and then you have the job done right. Many people don't realize it, but gaskets have thickness and that thickness may very well play a critical part in aligning the two pieces. Substituting liquid goop can decrease the spacing to the point that things bind up or otherwise misfit. That goo can also get into places you definitely don't want it and ruin things. I've seen a number of repairs that failed because someone used silicone and little bits of it came loose later and plugged up something.

When you take the sender unit out, be extremely careful handling it. The variable resistance coil in it is connected to the sender body by the thinnest of wires and can break loose very easily. It is so fine that it is a nightmare to get soldered back - this is what broke on mine so I have the first-hand experience. Unless you have practice soldering tiny little integrated circuits and the appropriate tools you'll never be able to do it, so avoidance of the problem is strongly indicated.

 

[TruChaos]

Not sure what "all those wires" and "realigning the hood" means. If I recall, there are only three wires,

And if you plan to replace the original machine screws with self-tapping sheet metal screws, you might end up making things worse.. //greg//

The Jinma is a 2004 284 with individual gauges and multiple switches on the dash. The dash cowl would have to be removed which of course is connected to the hood. The forward or rear position of the hood (latch release position) is determined by where the dash cowl is bolted. Of course to get to those bolts the hood has to be open/off so you can get to them, which of course makes alignment a pain.

There are separate wires for every gauge and switch, all of which are bolted onto studs with what looks to be 6 or 8mm nuts. The switches use non-keyed connectors which can be put on backwards during reassembly. So the cowl/hood is not exactly quick to remove and replace properly. Nor without potential damage to the wiring. Wiring doesn't scare me as I do it for a living but the quality of the wiring on the 2004 Jinma scares me a lot. : )

The screws I mentioned are the same as the factory machine screws but with hex heads (Lowes hardware) instead of phillips heads, so now no fumbling with a screwdriver up under the cowl. Just get them started and use a 1/4" ratchet to carefully finish them off.

 

[greg_g]

The Jinma is a 2004 284 with individual gauges and multiple switches on the dash. The dash cowl would have to be removed which of course is connected to the hood.

That's what I'm trying to tell you. I had early Jinmas too, individual gauges like you describe. The cowl is almost certainly the same. But I did not find it necessary to remove either the hood or the cowl. I had sufficient clearance with the little ratchet and screwdriver tips to completely remove the sending unit from the tank and outside the cowl. There are only 3 wires associated with the sender. Why make this more difficult than it has to be?

If you've already inserted one of those Lowes machine screws in there to the hilt - without cross-threading - fine. But if you try to force SAE machine screws into the metric tank threads, you're lookin' at an even worse leak to result

//greg//

 

[SPIKER]

lowes also carry metric bolts so that is probably what he is talking about.

dont use the silicone goop for gasket material, the chance of getting some in the fuel tank and into the strainer & plugging it up is a chance for problems. I had to fix mine just after assy. same issues fuel sloshing over top onto sender tank top & over. I have 2002 JM284 with individual gauges as well.

I made a new gasket our of proper gasket material, and did dab the screws into some silicone sealant as they seemed ot be the culprit for the leaks on mine as the fuel slosh would make bubbles around the screws as I shook the tank some with it full.

I also have a leaky second plug (there is a drain plug on the right side bottom of mine that also leaks some. I've fixed it 3 times and it always leaks some (not a real lot but will mess up a floor...) It has cross thread problems from the factory. I pulled mine form a crate so know it was not ME or a Dealer...

Mark

 

[TruChaos]

If you've already inserted one of those Lowes machine screws in there to the hilt - without cross-threading - fine. But if you try to force SAE machine screws into the metric tank threads, you're lookin' at an even worse leak to result//greg//

I'm not sure why you're not understanding what I'm writing but I've been pretty clear that I've purchased that same exact size screws (except with hex heads) as replacements. If my memory serves me they're 5 x .8 x 10 mm . There is no cross threading, they are the same size and pitch. I replaced them so it would be easier to install them with the dash cowl in place (I don't intend to remove it). As I said a couple times, removing the dash and hood is too much of a hassle unless I absolutely have to do so.

What's the matter Greg, it sounds like something is bothering you? I've read your posts for years and lately it seems like something is weighing heavily on your mind.