No Start Help for New ALH owner

Hey folks,

I'm new to diesels in general and to this forum.


I recently bought an 84 Vanagon with TDI, internet friends on the Samba said it's a MarkIV TDI.







I am rehabbing the Van, staring with brakes, including the booster, which required removal of the dash.


The Van would always fire right up... Until I put the dash back on. Now it cranks but does not start.


I have looked at the wiring, and everything looks ok, so I'm going to just troubleshoot this. "what does it take to make a diesel run?"
Fuel, air, compression, and "spark" -- right?




My (new) understanding is that there is no fuel pump, only the Injector Pump.
I tested the fuel flow out of the filter with a mighty vac and that looked good.



I found a video on testing the glow plugs.
With the key on, I get no power (using a test light) to the glow plugs.





I DO however get power to the Injector pump wire with the key on:





How do the glow plugs get power?
What do I test next?


Thanks!
Nick

Glow plugs get those power from the harness that plugs into them, they are mainly used to pre heat the cylinder to help with cold starting.

There is no “spark” on a Diesel engine. The compression of the piston raises the temperature inside the cylinder as it compresses the air and the temperature reaches a high enough temperature to ignite the fuel that is sprayed into the cylinder by the injector.


Sent from my iPhone using Tapatalk

So I have a feeling this is an "early" style Mrk4, and there is no harness that plugs into the glow plugs.


Is it a valid test that the glow plugs should have 12 volts to them, as I test above in the pic?
Or do they just come on for a brief moment when you first turn the key?

I just primed the fuel system by putting my MightyVac on the return side of the injector pump.
It fired right up (with some black smoke).


but I'm seeing some bubbles in the "Clear Window" aka fuel filter.


https://photos.smugmug.com/VehiclesOwned/TheBus/i-xJXFDQh/0/ea7b0171/640/IMG_9120-640.mp4

For reference sake that may be an ALH block but not an ALH injection pump, as it has a throttle cable and a boost-actuated fuel adjustment dome on top.

Typically folks refer to this as a "m-TDI" or "mechanical TDI"... no ECU, very little electronics, mechanical throttle.

The injection pump itself will likely be a Bosch unit from a Land Rover or some other vehicle modified for use with a VW TDI block... perhaps the folks you bought it from have more information. There will likely be a Bosch part number on the side of it, but it will likely have had internal modifications as well.

Worth tracking this info down, since you'll need it for future troubleshooting... a large part of how well the system works will depend on the skill of whoever did the conversion.

In terms of the air, yes, that's not normal... although neither is the clear filter you're seeing the air in. Not unusual for conversions and engine swaps to have non-standard plumbing.

You'll need to go thru the fuel system clamp by clamp... unfortunately we can't be much help because it's a one-off homebuilt system unique to that conversion. That said, if you have a large metal fuel filter with a black plastic tee on the top the two o-rings that seal the tee in place are frequent fail leak areas.

I'd also remove that crimp clamp visable in the video and try a clamp you can tighten.

Edit: blew up your engine compartment picture a bit and your metal fuel filter is an older Rabbit style that has no plastic tee... no joy there. The fact that the lid of the injection pump is black with dirt suggests the pump itself may be leaking... in particular, the shaft seal can be disturbed when the pump is being rebuilt and it will suck air as opposed to leak fuel.

Power is fed into the glow plug (5 or 7 volts via a harness), not out from it. If you don't have a harness, then it never was a part of your engine's operation, but I always thought the TDI needed operational glow plugs to start.

This is a conversion, so I'm thinking all bets are off in terms of how it's wired.

The stock ALH glowplug system is 12V (not PCM)... but again, all depends what the people that did the conversion had in mind.

OP: you won't find power on the directly at the glow plug itself, if that's what the picture shows you testing. Check for power at the wire that plugs into the glow plug.

That said, a TDI in good condition will start near freezing or above without glow plugs.

Some detailed pictures of the engine compartment itself will be handy if we're digging in further... no way to know over the interwebs details of the conversion itself.

ToxicDoc said:

Power is fed into the glow plug (5 or 7 volts via a harness), not out from it. If you don't have a harness, then it never was a part of your engine's operation, but I always thought the TDI needed operational glow plugs to start.

Click to expand...

direct injection starts good without them down way low in temp just fine, only really need them when you start losing compression from wear, or when it's 20 below and the battery ain't giving enough juice to get the motor spinning fast enough
ETA: when it is warm out, mine starts fine with supremely poor quality fuel and cut pistons for lower compression, the glow plugs are manual, and I don't bother with them


clear filter is on return side, air has to be coming from either pump input seal, or more likely from the inlet line somewhere
fuel tank empty?

I’d first try replacing that compression clamp right next to where the bubbles are showing.

hadn't watched the video, thought bubbles were while engine was running, not while applying vacuum to return line

spray connections with water to see if the bubbles stop

[486] said:

spray connections with water to see if the bubbles stop

Click to expand...

I would not spray water to see if it stops the bubbles.
Water in the fuel system is really not good.

I might use a drop of oil or such.

wonneber said:

I would not spray water to see if it stops the bubbles.
Water in the fuel system is really not good.
I might use a drop of oil or such.

Click to expand...

it really doesn't matter at all, the fuel filter holds about half a qt before it'll start passing it on to the engine

You guys are great! Many thanks. As I said I'm totally new so this really helps.

Vince Waldon said:

For reference sake that may be an ALH block but not an ALH injection pump, as it has a throttle cable and a boost-actuated fuel adjustment dome on top.

Typically folks refer to this as a "m-TDI" or "mechanical TDI"... no ECU, very little electronics, mechanical throttle.

...

In terms of the air, yes, that's not normal... although neither is the clear filter you're seeing the air in. Not unusual for conversions and engine swaps to have non-standard plumbing.

...


I'd also remove that crimp clamp visable in the video and try a clamp you can tighten.

...

Click to expand...

Done. I removed the crimpity-clamp and put on a band clamp. Still getting air bubbles. This is a big learning experience for me, and I'm liking the diesel more. So simple.

Vince Waldon said:

...
OP: you won't find power on the directly at the glow plug itself, if that's what the picture shows you testing. Check for power at the wire that plugs into the glow plug.

That said, a TDI in good condition will start near freezing or above without glow plugs.
...

Click to expand...

No wires connected to the glow plugs at all. I can post up some more pics.
I might wash it up though.

[486] said:

...

clear filter is on return side, air has to be coming from either pump input seal, or more likely from the inlet line somewhere
fuel tank empty?

Click to expand...

Indicator level shows almost half a tank. I think the air leak is causing the fuel to drain out of the IP.


Much appreciate all the help! I was freaking out that she wouldn't start

Without glow plugs if the engine has good compression it will start down to freezing or below without too much trouble. Will probably smoke white a bit on start, but otherwise should fire right up.

Since that's a manual pump conversion there's no ECU, which is what controls the plugs on a standard ALH. You could put a manual switch on the dash for very cold starting and pre-heat it a bit (sort of like you do a boat generator) if you want, but until it gets down to freezing or below you won't need it.

The air leak in the fuel system you do want to find. If you get air into the pump the wrong way it can make for very hard starting and, in some cases, a no-start at all.

if you do end up wanting to connect the glow plugs to something, there are standard crimp on terminals available. you want "female bullet style" connectors, and there are two sizes available so make sure and bring a spare glow plug to the radioshack

Those connectors + a high current relay (garden tractor or starter solenoid rated for *continuous* duty) and a switch on the dash and you've got manual glowplugs just as good as the automatic version, for 20 bucks.

One way to do the wiring:

http://vincewaldon.com/index.php?option=com_content&task=view&id=30&Itemid=28

Tdijarhead said:

I’d first try replacing that compression clamp right next to where the bubbles are showing.

Click to expand...

I did this, and have not had any problems since.

I also when through and made sure the other clamps were tight.


I still get some bubble when it shuts off, but it has not prevented starting.

It actually fires right up and is an impressive little beast.
Ok, it's not a beast.

After watching the video and looking at a blow up of the engine compartment I do not think you need the small filter.

The big metal one filters fuel from the tank.

I did not have the small one on my old 1.5 / 1.6 diesels which I think you may have.
If think the engine code (3 letters) are on the block if you look down the back of injection pump just above the oil pan.

From post 1: 'Now it cranks but does not start.'
If it ran before you removed the dash I would think it's a power to the pump issue but your picture shows power.

Can you have someone crank the engine while you check that you do not loose power?

Last, crack the injector nuts loose a 1/4 turn or so and crank the engine.
Do you get fuel squirting out of the lines?
Have some rags under the injectors to catch the fuel.

Last, is there a turbo on it?
Should be under the intake manifold.

swissarmychainsaw said:

I found a video on testing the glow plugs.
With the key on, I get no power (using a test light) to the glow plugs.

Click to expand...

I seem to recall there was a copper bus bar running across to each glow plug with nuts holding it on. on the old 1.5 / 1.6 diesels which the 84 may still be.
Someone here may correct me if I'm wrong.

My old Bentley covered 77 to 84 which it what I'm going my.

It's a transplanted ALH engine (converted to m-TDI), so would use the standard plug-in black plastic harness.

For whatever reason it looks like the people that did the conversion missed the glow plug system.

OK, you clarified that.

Andy B should be able to correct me if I'm wrong:

I would think you should have the spot to plug in the glow plug relay in the relay panel.

You might have to connect 2 or 4 of the plugs together to 1 or 2 wires that go to the controller.

Keep in mind the ALH has a 50 amp fuse for this!
Don't run light wire for this if you have to.

A relay in the back with a push button in the dash might be an easier mod if you have to.

Yup, whatever glowplug wiring the 84 chassis came with from the factory at the front end should work just fine... other than the temp sensor it's expecting might be a different calibration range than the ALH CTS.

Manual pushbutton probably the way to go, for multiple reasons.