Fuel dribbling from the heat exchangers *Now with pics*

[Htotheunit]

Hi everyone!

After a long winter in dry storage I went to take my van out for the summer. After a while the van did start for a few seconds (as expected, the battery was fairly low) however when I looked under the van there was a puddle underneath the right hand heat exchanger. I sniffed the puddle (as you do) and discovered it was fuel :shock:

To cut a long story short, every time I turned the engine over, fuel spilled out of a small hole between the heat exchanger and exhaust manifold (yep, I now need a new manifold/heat exchanger)

Is it normal/possible that I accidently flooded the engine whilst trying to start it and the fuel will just evaporate/burn off out of the exhaust or is this part of a much bigger problem?

Thank you in advance guys =)

 

[mattd1984]

If you did flood it the fuel would just evaporate. Sounds like a leak in the fuel line between the tank and the engine bay and its just leaking onto the heat exchangers and then onto the floor. Have a look under the van. Is the fuel filter in the engine bay or above the gearbox?

My guess is the lines are rotten and leaking. Get some good new ones from volksbolts there really good lines.

 

[Htotheunit]

Nope, it's not a fuel leak! I had another look and it only comes out when I pump the accelerator when trying to start it. If i am flooding the engine, is fuel likely to exit via the exhaust system?

 

[type2tattoo]

Nope, it's not a fuel leak! I had another look and it only comes out when I pump the accelerator when trying to start it. If i am flooding the engine, is fuel likely to exit via the exhaust system?

No! you have definately got a leak! and will have a fire very soon once the heat exchangers get hot :shock:

 

[Htotheunit]

Yes I know fuel means fire, hence the bus still being laid up until it's fixed! I honestly think the fuel is coming out of the cylinder unburned and exiting through the exhaust system (through the heat exchanger) who has fuel lines above the heat exchanger? Not me that's for certain!

 

[mattd1984]

When the fuel line come out of the tank it does pass above the heat exchanger then goes into the engine bay. Is it the left or the right heat exchanger it is dripping off?

 

[Frisco69]

Do you have twin carbs? It's not leaking from one of those is it. Maybe running down the the back where you cant see it?

 

[Htotheunit]

When the fuel line come out of the tank it does pass above the heat exchanger then goes into the engine bay. Is it the left or the right heat exchanger it is dripping off?

It's on the right hand side heat exchanger (if looking from the back) the fuel lines run down the left don't they?

 

[Htotheunit]

Do you have twin carbs? It's not leaking from one of those is it. Maybe running down the the back where you cant see it?

Nope I got a stock carb

 

[Htotheunit]

Here we are, The substance on the tappet cover above the heat exchanger doesn't smell like fuel, it appears to be oil.

The fuel leaks out of the little crack in the 1st image where the exchanger is supposed to attach to the header

 

[mattd1984]

Is there any sign on fuel leak inside the engine bay?

I would get those rocker covers changed and fit new gaskets this should stop the oil leaking from them onto the heat exchangers.

 

[Frisco69]

Just had a read through again.

You are certain it's coming out of the heat exchanger so assuming you are correct it could be you have a burnt out exhaust valve on number one or if it's not run for a long time corrosion around the valve seat so when the fuel and air is being compressed it is getting pushed straight passed the exhaust valve and leaking at the joint between head and heat exchanger or a hole further along.

Did it sound light on compression when you tried to start it. Do a compression test if you can.

 

[Htotheunit]

Just had a read through again.

You are certain it's coming out of the heat exchanger so assuming you are correct it could be you have a burnt out exhaust valve on number one or if it's not run for a long time corrosion around the valve seat so when the fuel and air is being compressed it is getting pushed straight passed the exhaust valve and leaking at the joint between head and heat exchanger or a hole further along.

Did it sound light on compression when you tried to start it. Do a compression test if you can.

It did start for a couple of seconds, however the battery was rediculously low and unable to
Keep it going.. If what you have suggested, how would I fix this? I'll get my brother to charge the battery and give it another whirl and see if it sounds like it's not compressing correctly. It certainly does seem like cylinder 1 is chucking the fuel out into the exchanger

There's nothing in the engine bay that I can see that would suggest leak, however I will give everything in there a clean (it's all a bit grubby) so I'll have another look, but what you said sounds about right.

Thanks

 

[Frisco69]

Just had a read through again.

You are certain it's coming out of the heat exchanger so assuming you are correct it could be you have a burnt out exhaust valve on number one or if it's not run for a long time corrosion around the valve seat so when the fuel and air is being compressed it is getting pushed straight passed the exhaust valve and leaking at the joint between head and heat exchanger or a hole further along.

Did it sound light on compression when you tried to start it. Do a compression test if you can.

It did start for a couple of seconds, however the battery was rediculously low and unable to
Keep it going.. If what you have suggested, how would I fix this? I'll get my brother to charge the battery and give it another whirl and see if it sounds like it's not compressing correctly. It certainly does seem like cylinder 1 is chucking the fuel out into the exchanger

There's nothing in the engine bay that I can see that would suggest leak, however I will give everything in there a clean (it's all a bit grubby) so I'll have another look, but what you said sounds about right.

Thanks

Take the valve cover off and turn the engine with a 30mm spanner (make sure it's out of gear). Watch the exhaust valve to make sure it closes fully. It could be stuck open slightly.

Do a compression test if you can on all four cylinders. If number one is way down then there is a problem.

Was it running ok when it was laid up? I think you mentioned it's been laid up for a while so the valve could be stuck open slightly or seats are corroded. If they are corroded cranking it over for a short while with fuel disconnected is sometimes enough for them to beat back in and reseal. Like wise cranking it over may free off a stuck exhaust valve.

I hope I'm not giving you a bum steer and making more work for you but I think you need to look into it if you are certain there is no external leak.

And if fuel is leaking out of the exchanger you must have a hole which means obviously exhaust gases will enter the cabin but first things first.

 

[BJ1]

If the fuel is really leaking out of the manifold then it's likely that the needle valve on the carb is stuck open allowing fuel to drip down the intake. So take the top off the carb (six screws) and check the fuel level in the float chamber. My guess is that it will be brim full. If so then just renew the needle valve. This happens a lot when buses are laid up for a while with a lot of fuel in the tank.

Brian

 

[ronmidg]

maybe i'm being super dim today but there is a couple of things I dont understand

when the engine is not running how does fuel get from the inlet system into the exhaust system without going via the cylinder, and partially filling the cylinder enough to drain into the sump?

if fuel is coming out of the heat exchanger at the exhaust pipe holes then doesnt this imply the exchanger is half full of fuel, a lot more than pumping the gas pedal a few times?

 

[Htotheunit]

maybe i'm being super dim today but there is a couple of things I dont understand

when the engine is not running how does fuel get from the inlet system into the exhaust system without going via the cylinder, and partially filling the cylinder enough to drain into the sump?

if fuel is coming out of the heat exchanger at the exhaust pipe holes then doesnt this imply the exchanger is half full of fuel, a lot more than pumping the gas pedal a few times?

It only comes out when i turn the engine over.. and as for the second question.. I have no idea!

 

[Frisco69]

It is going via (or atleast it should) the cylinder. I don't think anyone said it wasn't.

A bit more investigation is needed to determine the problem. Hopefully it is leaking unseen above the heat exchanger which would be easier to fix.

Let us know what you find hasthespaz!!!!