Fuel leak from intake valley

[Hasdrubal]

So, noticed fuel down at my bellhousing cover drain hole and at bottom of starter next to block. Its draining down from the intake valley. Took off air cleaner assembly to get a better look. All the lines at the IP are dry, it looks like its coming somewhere halfway down the valley. I suspect the rubber lines from the filter base or the hard line coming up from the lift pump. Couldn't tell where it was from so I cleaned it all up to get a better look at where its leaking tomorrow. It didn't seem to be the supply line to the IP.

If its just one of the rubber fuel lines, are these the correct sizes ( Fuel filter lines at filter base; 3/8 in to the filter and 1/4 inch to the injection pump)? If its possibly the hard line developed a crack or pin hole. Where would I obtain one, in the TM's it says; 16 MFFZZ 11862 14061503 TUBE ASSEMBLY,METAL (35.52"LG) MAKE FROM TUBE, P/N 3750950. Can this tube be replaced withought major disasembly? I noticed that the upper filter base rubber line from lift pump metal tube tube is preformed.(PAOZZ 11862 14063301 HOSE,PREFORMED) It has a bend in it less than an inch from the bottom end that attatches to the lift pump tube, looks like its for clearance to the CDR bracket. Ever sourced one of these? Can one use regular line?

 

[hokie8358]

i had a similiar instances with my 84 m1008. i saw the same signs as you. mine turned out to be the throttle arm or lever on the lower left of the inject pump. its an o ring that can dry rot with time. and it will get eventually to were it wont run at all. diesel care in tenn. hooked me up on rebuild for only 255 bucks and shipping and all. and they stand behind it. my old one lasted bout 8 months before it petered out.

 

[condor418]

Im not sure how different the fuel system in on the 6.2 but on my civy chevy 2500 6.5 on the bottom of the fuel filter housingand there is a fuel heater and the rubber around the wire goin into the housing turned to mush and fuel was pouring down the back end of my engine... i was more then 1/2 thru pa on my trip from nj to az so i cut the wire and plugged the hole with a steel fuel tank repair kit that was almost 2 years ago never got around to fixing it for real

 

[BIG_RED]

You can use a piece of 3/8" brake line to replace the fuel line. The fitting on the pump is the same. Just have someone bend it to match. I replaced mine with a rubber line that runs off the engine to the front battery tray and along the passenger side fender (where the auxiliary electric pump is about to be installed) to the firewall mounted fuel filter. I did not like how close the hard line was to all the "spinning stuff" (belt system) on the front of the engine. 1/4" and 3/8" are indeed the correct sizes. You can reach in from the back of the cylinder valley with your arm under the intake manifold to replace the 1/4" feed to the IP. That is usually easier than removing the intake manifold since the manifold has about 17 bolts holding it on (ask me how I know ). Good luck.

 

[Hasdrubal]

Well...the IP, all its lines and the valley underneath it are all dry. It really seemed to be coming from the pre-formed hose between filter housing and lift pump hard line. The 1/4 IP hose looked dry. I suppose my question would be to anyone who has had to replace it. Can you use regular 3/8 fuel line. I'm concerned about this preformed bend to clear rubbing against the CDR bracket. I'll know more tomorrow afternoon when I get home and check it out again.

 

[Hasdrubal]

As the only wet area I could find where a leak could occur, I replaced the rubber line between lift pump hard line and fuel filter. Sourced a spring that fits around the 3/8 fuel line so it wont wear a hole rubbing against the CDR mount bracket. The old hose actually looked pretty good, with just a little cracking at the edge which I'll assume continued underneath where the clamp sat.

After driving today, I checked underneath. Couldn't believe it, it had dripped fuel onto the front driveshaft again, also coming out of the bellhousing drain and collecting on the block side of the starter. So... off comes the air cleaner assembly and I spend an hour looking for a source. Nothing, no lines are now wet in the valley. From up top there is no sign of a leak.

Underneath with a trouble light is the same story, no obvious sign of where the fuel is coming from. All injectors, hard lines and IP remain dry. The only sign of the previous leak is the top of the bellhousing is stained towards the passenger side where the valley drain is.

Put on a some ear protection and spend 10 minutes leaned over the running still hot engine with the air cleaner assembly off. Absolutely nothing, I suppose enough fuel could have been sitting in the bellhousing cover due to its curved shape. But the fuel collecting at the bottom of the starter leaves me mystified. Going to drive it tonight, check it again in the morning. Very odd.

 

[ranchhopper]

Its your pump or maybe a line leaking behind the pump had it happen to me bottom injector line on the back of the pump had to tighten it up.Stuff a rag under the IP and go for a drive and see if the rag has fuel on it when you get back.

 

[Carpenter]

I had the same symptoms as you. I replaced the fuel line feeding to the IP and tightened it down good. That stopped any signs of leaking there but when I parked the truck I'd still get a few drips of fuel on the driveway. I found that when under load there was a leak in the IP and it would fill the valley below the intake with diesel.

My thought was rather than trying to replace a gasket or o ring here or there, I replaced the IP.

I should also note that I was having trouble starting the truck as it was losing prime after it had sat for a few hours.

A new IP and air filter and she's got all sorts of power now

 

[ixpacman]

I had the same problem when I had blown my 6.2 in my 1008Replaced motor in a hurry and had a corroded line from lift pump to fuel filter. Also had a few injector line leaks at fitting on IP pump.After trying everything possible to tighten fittings with assorted line wrenchs crows feet and anything else I sxtill had leaks. Reluctantly I pulled the intake for the second time and removed all injector lines and cleaned the little ball shaped seats on a wire wheel and retorqued all fittings carefully and reassembled all the lines and chafe protection and associated brackets . Started her up and still had fuel coming out the bell housing which comes from a small drain hole at the back of the intake valley.Crap!! The next day I had to drive the truck to fort Drum to pick up Two ISO 090 containers with a trailer. 700 mile round trip! After using mirrors and various inspection lights I managed to see the leak. A pin hole in the fuel pump to filter line.I temporarily bypassed it with rubber hose. When I got back I pulled the intake again and replaced the line with a spare I had from the old engine but regular brake line could be used but the bends have to be perfect to avoid any chafing.When I got it all back together I was adjusting the passenger side alternator belt tension and my prybar shorted the alternator to the fuel return line and burned a hole in it. obviously my frustration was causing me to be hurried and careless at this point and needless to say it was time to go have a beer and think about something else. Anyway lesson was when you have the intake off of a 6.2 check everything first.If you are careful you can run a 6.2 without the intake on and check quickly for fuel leaks before you put everything back together. Even though I wouldn't recommend this to anyone it was a good way to insure that I wouldn't have to take the intake off again.

 

[Hasdrubal]

Well, drove last night for 30 minutes, just checked underneath. Barely a minor amount of discernible wetness. Will take it out for longer today. Of course my main suspects remain the filter to IP 1/4" rubber line at the IP end and the hard line from lift pump to filter. This line is hard to see tucked in along the passenger side of manifold. Anyone know where one of these can be bought if needed. Or is it unavailable new, if so how about a used one.

It seems to be a leak from the low pressure side of the system as I'll assume a leak from a high pressure line would spray everywhere.

 

[Hasdrubal]

Well to end this story. It seems that the 3/8'' filter input rubber line was the source of my leak. I also managed to get my arm under the manifold and tighten the clamp on IP input. Didn't replace it yet becuase it looks fine, so I'll leave it for now.

Drove last night for a couple of hours with a rag in the valley, it was completely dry. No more wetness from the bellhousing drain and just a single spot diesel and oil mix at the bellhousing protrusion where the starter nose goes in. Ill assume thats a little residual that has collected in this small bowl shape and comes out from being on steep inclines. Will still keep an eye on it for the next few days...bit it seems to be rectified.

 

[Carpenter]

Gotta love an easy and inexpensive fix. Good stuff

 

[Hasdrubal]

Well..perhaps I spoke too soon. A closer look just now at what is still collecting at the front of the starter shows it to be engine oil, there is no smell of diesel, and intake valley is completely dry. Rather than start a new thread, I'll continue here. Sure there are plenty of minor oil weep marks all over this engine but never enough to start drippng down the block and on the ground. Actually its right at the starter then drips on front driveshaft.

I've looked this engine over from every possible angle but there just isn't any indication at all of any source of this leak. I think I'm going to have to get one of those little adjustable mirrors with a long handle so that I can see the side of the block better above the starter. I recall hearing a story about the vacuum pump leaking oil from someone. Anybody have any experience with this? I'd like to know what seals this pump and if it just come straight out and goes back in. Its in the right area and while there is no oil trail off it, there is a stain on the bottom 2 inches from an oil leak. Maybe I'll have to wrap a rag around it at the bottom to see if its the culprit.

 

[Terracoma]

Could it be coming from the very rear of the valve cover on the passenger side?

I've got a (similar) single drop of oil hanging from my starter every time I look under there, but never a drop on the driveway...

 

[Anubis8472]

Try cleaning your CDR and oil fill cap.

Mine started loosing a good deal of oil, but only while driving.
Could sit for days and not a single drip.

Replaced CDR and oil fill cap and no more leak.

I still have some minor seepage in a couple spots, will be replacing the oil pan gaskets soon. Until then I just consider it rust prevention.

 

[Hasdrubal]

Yes, it has a brand new CDR valve, oil cap has been cleaned and tested OK. Being at the passenger rear, I checked the back of the valve cover by wiping it with a white rag, no fresh oil mark. Its another one of those, only leaks when you're not looking at it scenarios. I'll be inspecting it every day after driving now to figure out where this leak is coming from.

 

[appnut1]

The vacumm pumps can leak from an o-ring around the base and also can leak out the vent holes on the back of the diapram when it fails. Comes out and goes in like a gas engine distributor and does not requiring timing.