[QUIKDZL]

I've finally put two and two together, and I think I've found a correlation. Soon after my tune and water/meth installation. I had an instance where the engine took a few seconds of cranking before it started. I consulted Bob, Lord of Horsepower, and he thought it was likely the new EGR map in my Clean Tune in relation to the particularly cool morning. That wasn't the cause, though.

Since then, I have had four more instances of difficulty starting after having been parked for several hours. I have found the common denominator. I believe it is heat soak in the water/meth line. Each time this has happened, it was preceded by a really fun fuel-sucking, high-boost, meth-spraying run. While parked, I believe the meth line and its contents heat up, causing the mixture to expand. The solution can't flow back into the w/m tank because of the check valves at the pump, but it can seep through the check valve behind the spray nozzle and dribble into the intake, likely pooling in the intercooler. My set-up uses a (reversed) check valve rather than a solenoid valve behind the nozzle.

What is puzzling is that there couldn't be more than a tablespoon of w/m that dribbles into the intercooler, but it makes the car very hard to start eight hours later. Can someone explain how such a small amount of water in the intercooler causes such difficulty starting? It'll crank over for 3-6 seconds, and then idle like its running out of fuel. After about 30 seconds, all is well.

None of this happens under "normal" driving.

[335dlci]

How long is your meth line from the solenoid to nozzle?

[iaknown]

I've encountered something similar but not to the extent that you're describing. I've noticed extended cranking (maybe a few seconds extra) if I've previously been running the car hard with meth before shutdown. After the car starts it idles fine though.....

[Hoooper]

I have the same thing, I've learned to run the engine an extra couple minutes diving around normally to eliminate it. My extra cranking is only a half second or so, but my line after the solenoid is only about a foot and a half so there's very little meth to leak in.

[335dlci]

hooper. as you mentioned about your line length, mine is about the same and I have same problem at times. I have also idled my car to let temps go down and have had it stall a few times after using meth.

[Whitbread]

I've noticed giving the car a mild ~50% throttle rip through a gear or two (with meth off) will get rid of the funny start up after doing some good meth runs. Otherwise, mine will crank for an extra second or two and stumble a touch for a brief second. Then all is back to normal

[kydiesel35]

Originally Posted by Hoooper

I have the same thing, I've learned to run the engine an extra couple minutes diving around normally to eliminate it. My extra cranking is only a half second or so, but my line after the solenoid is only about a foot and a half so there's very little meth to leak in.

+1

Do a few pulls without before shutting down... I like to let it idle for a couple minutes as well. If you don't already have a switch somewhere in the cabin to disarm the system get it done.

[WreckerX5d]

Happens as well to me. Either idling it longer or parking on a decline helps out.

[QUIKDZL]

Originally Posted by 335dlci

How long is your meth line from the solenoid to nozzle?

Mine's a check valve, not a solenoid valve, and the line is about an inch long. Because it's a check valve, the entire line underhood is subject to heat soak and seepage.

Originally Posted by Hoooper

I have the same thing, I've learned to run the engine an extra couple minutes diving around normally to eliminate it. My extra cranking is only a half second or so, but my line after the solenoid is only about a foot and a half so there's very little meth to leak in.

I'm doinig the same and haven't had an issue in over two weeks. Three times it was also minor. Once, however, after a really fun ride, it took two attempts and about 15 seconds of cranking to start it up, and then it ran on one cylinder for about 30 seconds before returning to normal. That was the last time.

I still want to know why this small amount of water/meth in the intake prevents combustion. DWR?

[DWR]

Neither methanol nor water are going to help during cranking. Remember, when cranking the intake is under vacuum. Too rich a mixture will not autoignite. In addition, a 16:1 compression does create enough heat to cause methanol to autoignite. Water has a very high heat capacity. Even a small amount will significantly reduce the heat generated during compression. That heat is needed to autoignite the diesel.

Because it is relatively warm this time of year where you are, I'm wondering if the DDE is depending primarliy on cranking power to heat the cylinder. At any rate, the engine will crank until it gets enough heat and the right air to fuel ratio. But just like a gas engine cranking can cause flooding. That just makes it worse. Diesels have a wide AFR operating range so that does not usually happen ...

[Nadir Point]

There's an engine temperature window somewhere between hot and warm that does not signal glow plug activation and is also not quite hot enough to light right off when you hit the starter. It causes a long crank of about 3-5 seconds. This might not be what you guys are experiencing, but something to think about next time it happens. For my car it's at a point somewhere around 15-30 minutes after shutdown on a moderately cool day. I've not actually tracked it for documentation purposes because it's a moving target depending on ambient temperature, but nevertheless, a predictable and reproducible phenomenon having nothing to do with W/M.

My W/M system is designed with check valves screwed in right behind the injector as a single assembly and the lines travel downhill from there. This setup prevents leak-down from going to the intake.

[335dlci]

Originally Posted by UberArchetype

There's an engine temperature window somewhere between hot and warm that does not signal glow plug activation and is also not quite hot enough to light right off when you hit the starter. It causes a long crank of about 3-5 seconds. This might not be what you guys are experiencing, but something to think about next time it happens. For my car it's at a point somewhere around 15-30 minutes after shutdown on a moderately cool day. I've not actually tracked it for documentation purposes because it's a moving target depending on ambient temperature, but nevertheless, a predictable and reproducible phenomenon having nothing to do with W/M.

My W/M system is designed with check valves screwed in right behind the injector as a single assembly and the lines travel downhill from there. This setup prevents leak-down from going to the intake.

I just have a solenoid with about a foot of line to the injector. I don't think they have a built in check valve. Where to buy?

[Nadir Point]

Originally Posted by 335dlci

Where to buy?

I got some nice little brass 2psi models perfect for this application from McMaster Carr:

Check Valves

[335dlci]

Originally Posted by UberArchetype

I got some nice little brass 2psi models perfect for this application from McMaster Carr:

Check Valves

[slim25073]

Hi Guys
Was there a solution? Have the same issue. I reduced my nozzle have a check valve between. It’s terrible now the cranking and the car just shuts off.

Any new methods happy to try out.

[QUIKDZL]

I think the general consensus was to do whatever is necessary to prevent water leaking into the intake when it is not being sprayed. A cooldown period after a run is the simple solution (all other leaks being fixed), but if I were building a race car and aesthetics and budget weren’t concerns, I would install a small expansion tank between the positive displacement pump and the check valve at the injector. Or add a valve-actuated drain line bypassing the pump back to the tank.