85 Jetta engine swap

Diesel Dean · Post by **Diesel Dean** » Wed Jan 16, 2008 9:03 pm

I am installing a diesel engine in a gas 85 Jetta. Should I remove the fuel pump? I am just wondering if the injection pump will pull fuel past the pump. Also do I need to put a check valve between the tank and the injection pump? If so what does it look like? The transmission is a 9a13055 five speed will that be a good trans for fuel economy. ( low reving at 55 m.p.h.
Thanks

bscutt · Post by **bscutt** » Wed Jan 16, 2008 9:14 pm

I am no expert on that topic but my 93 Passat wagon with the eco diesel swap (I bought it wrecked) has the in-tank pump removed and it looks like the pickup was extended to where the pump intake was. I am having some trouble getting fuel up to the pump but I think that is due to a restriction in the line probably related to severe rear-ender. I have a low-pressure electric fuel pump helping out so it's easier to start and move around.

Anyway, I suspect you could bypass the in-tank pump and be ok. Leaving it in would be forcing some faily high pressure diesel up to the IP, probably around 30 psi or so. I don't know if it would allow any flow if unpowered and left in place.

Homer T. Coyote · Post by **Homer T. Coyote** » Wed Jan 16, 2008 10:08 pm

Looking in the Bentley, the gasser seems to have an external pump. I would remove the pump and connect the fuel lines to the top of the tank at the sending unit. Big line is supply and little one is return. There is an access door under the carpet in the trunk that should make this easy. Yes I would add some check valves to keep the pump primed. They are little plastic things that look like a motorcycle inline filter. Make sure you put the cannister filter in the engine compartment. A water separator would be a good addition as well but not mandatory. As for the 5 speed, there is no contest. 5 speed all the way. I get 43-45 mpg w/ my '85 TD Jetta.

ahistand · Post by **ahistand** » Thu Jan 17, 2008 2:50 pm

According to my info your 5th gear ratio is a .89 which is on the higher end of things, so not the greatest for mileage. But your final drive is a 3.67 which is pretty good. But there are even four speed trannies out there which have overall better ratios for mileage than this five speed. For instance I have a GP which has a .71 fourth gear and a 3.89 final drive.....a pretty good setup. Not great if you live in the hills though, especially with a NA motor.

Diesel Dean · Post by **Diesel Dean** » Thu Jan 17, 2008 3:13 pm

Thanks for the trans info I also have the GP four speed in my Rabbit and get 45-50 M.P.G. With the five speed I talked about i will have a little more power in top gear that good because my wife will be driving the car. If it were to slugish she might not want to drive it.
Thanks

Homer T. Coyote · Post by **Homer T. Coyote** » Thu Jan 17, 2008 9:31 pm

While were talking trannies, does VW have a six speed out there that would work w/ our dinosaurs?

82vdub · Post by **82vdub** » Thu Jan 17, 2008 11:55 pm

While were talking trannies, does VW have a six speed out there that would work w/ our dinosaurs

Yes, I've been wanting to know this too. However, I'm probably not interested in spending $1000+ for a newer trans plus $ for the swap at this point. But, I'd like to know if there's a manual 6 speed out there that anyone's used

surfcam · Post by **surfcam** » Fri Jan 18, 2008 1:19 am

Their's companies out their that will make your 5 speed into a 6. Its a kit that bolts onto the end of the tranny. I did see a web site that offered the service. I think it was in the four figures. Their was a guy in Calgary that had one and he wanted 1000 for it.

82vdub · Post by **82vdub** » Fri Jan 18, 2008 10:07 am

There's a company called http://www.gearvendors.com/ that makes adaptors that replaces the output housing on your transmission (or is added after the trans) and is essentially an overdrive unit, but I don't know if anyone makes anything for a transmission that essentially has two output shafts (for front wheel drive cars). I've wondered if you could take a 4 speed and make a 5 speed out of it as well.

ajt3nc · Post by **ajt3nc** » Sat Jan 19, 2008 1:19 am

I just did this. Leave the lift pump in the tank. ( Supposed 2-5 hp ??)
The rest is a straight swap.
Unless you have a gti tranny , you will pull less revs.
( Wannabe hot rods get the diesel tranny to drop gear ratios)
Bolt it up. Use the coil lead for the fuel pump check valve and wire up a glow plug relay.
I met a guy who uses the interior light to trip the relay.

EDIT
Rubber is cheaper than gears.

JRM · Post by **JRM** » Sat Jan 19, 2008 1:48 am

id love a gasser trans, heck on flat ground i shift from 1st to 3rd then strait to 5th on my close ratio trans, It screems so hard in 5th im forced to drive my honda civic on road trips as holding 85-90MPH all day long in the VW when I travel just screems the diesel to hard, Im not going to risk ridgeing my block holding my VW at redline that long so I use my VW for my local 105 mile round trip commute and my 02' civc for all commuting 500+ miles beteen Oregon, Cali and Idaho.
Good thing my company pays $0.49 a mile

42MPG city-63MPG on a slow flat roadtrip VW
35MPG city-42MPG highway civic (no joke) and unleaded is cheaper. It really does get 42MPG, prob the 0w20 moteroil and rock sold tires

Diesel Dean · Post by **Diesel Dean** » Sat Jan 19, 2008 5:50 pm

ajt3nc,
you are saying you kept the gas fuel pump in operation. It's not in the tank it's just on the out side near the fuel filter. Will it feed to much presssure the the injection pump?

82vdub · Post by **82vdub** » Sat Jan 19, 2008 7:05 pm

If the car had fuel injection, typically the fuel pressures to run the fuel injection system are much higher than what you would need to push the fuel to the front of the car. Hopefully someone who has done this conversion will chime in on this one.

ajt3nc · Post by **ajt3nc** » Tue Jan 22, 2008 2:03 pm

I had two pumps on my digifant gasser. A low pressure in tank pump I kept and the high pressure external pump I removed.

Post by **Fatmobile** » Tue Jan 22, 2008 10:07 pm

Do you have a pressure gauge on your fuel line?
My '91 Golf turbo diesel was a gasser and I've been thinking about putting the tank pump back in... along with a boost gauge on the fuel line so I could read positive pressure along with vacuum.