Another hard to start in cold temperature question.

murdermitten · Post by **murdermitten** » Wed Jan 03, 2018 10:26 am

Hello Everyone!

After pursuing just about every thread I could find on the subject I feel that I have a question worth asking, as I am trying to narrow down what has become a rather annoying problem.

I have a completely rebuilt 4D56T engine in my '90 L300 that runs near perfect, once it's hot. The problem is at cold start. I have to crank endlessly, and floor the throttle. The result is excessive smoke at startup, and occasionally the van dies and has to be turned over several times to idle on it's own. Using the idle adjustment does not seem to be enough to keep it from sputtering out when the temp is near 0C.

There are two concerns:

1. PLUGS: Post-rebuild the ECU does not automatically cycle the 6V plugs. So, I provided a "push to engage" button for the mechanic to override that system and heat the plugs, which it does, but they are old plugs pre-rebuild...neither he nor I have dug into this any further becasue the push button seems to work.

Multimeter readings on the plugs are as follows:
2.3 Ohms at rest (bus bar is 2.2)
7.3 Ohms when button depressed to engage plugs (bus bar is 7.2)

2. FUEL: I can prime the fuel filter 20-50 pumps before I stop, there is no fuel coming out of the bleed nut (I have done this with the nut all the way out, and just loosened. It has the hole drilled in the threads so it appears to be the original nut) As I mentioned a cold start requires heavy throttle so my thought is there is air in the lines but I do not know how to diagnose/repair. I've ordered a new filter and considered ordering a new primer pump (the "lid" for the fuel filter)

Before I just start jumping to conclusions and replacing huge parts of the fuel delivery system, what do you guys think?

sk66 · Post by **sk66** » Wed Jan 03, 2018 1:23 pm

The owners manual states that the throttle should be depressed for cold starts, I don't think that's the issue.
It's possible that there is air in the line, but I think it is more likely that the priming pump is faulty and that's why you're unable to get fuel from the bleeder. If it was getting air, it wouldn't have excess fuel when it finally lit off.

Are your glow plugs connected to the 6v solenoid, or the 12v solenoid (or direct)? The 6v system is designed to cycle the glow plugs w/ 6v after starting until things heat up enough to run smooth... you'll probably need to do the cycling manually.

murdermitten · Post by **murdermitten** » Wed Jan 03, 2018 2:27 pm

Thanks for the quick response sk66!

I did not install the push button for the plugs, but when depressed it causes the standard "click" that I experienced when the system worked through turning the ignition key. I can inspect a bit more and also check back in with the mechanic to see what exactly he did with the wiring.

As for the priming pump, I'm going to go ahead and order a new one. Do you think that would actually cause the air in the lines issue? Or is it merely a symptom of air getting in elsewhere?

Post by **Growlerbearnz** » Wed Jan 03, 2018 2:35 pm

So you're using the old glow plugs? Have you bench tested them to make sure they glow?

I'd check up on sk66's suggestion: make sure your manual button is connected to the 12V solenoid, not the 6V one.

Alternately, try using a jumper lead on the glow plug bus bar directly: apply 12V from the battery to the bus bar for about 7 seconds, then see if the engine starts any easier (do this after bench testing the glow plugs).

murdermitten · Post by **murdermitten** » Wed Jan 03, 2018 3:07 pm

Hi Growlerbeans-

By bench testing do you mean checking resistance? I'll bench test them tomorrow night. They should be pulling 0.7-0.9 ohms right (depending on the meters resistance of course)?

I can also bench test them like this, right?: https://youtu.be/IF0cb_ExkkE?t=28s (off of a 12V battery how long should it take?)

I recall the setup for the solenoids, but which one os 6 and which is 12?

: Screen Shot 2018-01-03 at 1.56.47 PM.png (49.84 KiB) Viewed 8073 times

Thanks as well for the jumper tip, but before I electrocute myself am I basically taking jumper cables, grounding both negatives, then one positive lead on the battery and one on the bus bar (for 7 secs)? Also does it matter which battery I connect to if I'm running the dual battery setup?

Thanks,

Eric

Post by **Growlerbearnz** » Wed Jan 03, 2018 3:32 pm

I would test them like in the youtube clip- resistance is nice, but seeing them glow is better. I would heat them, counting the seconds, until they glow a bright orange. I would expect it to take 4-7 seconds, but as long as they all glow in about the same time they're fine.

Don't drop them or treat them roughly. Wear safety glasses, just in case one shatters. It shouldn't, but you never know.

14616QG is the 12V solenoid. This thread: http://www.delica.ca/forum/viewtopic.ph ... id#p133525 shows the glow plug solenoids, but TL:DR; to apply 12V to your plugs for fast warmup you want your manual button connected to the solenoid with the spade terminal, not the solenoid with the phillips screw. (That's the 6V solenoid, which is used to keep the plugs warm once the engine starts).

For the jumper test, you only need the red cable. One end to positive of one of your batteries, the other end to the bus bar like so:

: BusBar.jpg (59.91 KiB) Viewed 8071 times

Be very careful not to touch the alligator clip to anything other than the bus bar. If you touch the head you'll get some very exciting sparks, if you touch an injection pipe it's ruined. Maybe put insulating tape on the outside of the clamp's jaws, and tuck a sturdy rag under the bus bar (covering all the earthed metal around the area).

feetforbrains · Post by **feetforbrains** » Wed Jan 03, 2018 3:55 pm

Just a thought: how cold is cold? If the fuel has gelled then it's going to be starved no matter how much you pump it. Mine is now way too tall to fit in may garage so I've been checking in on the fuel. D2 in the US isn't going to gel until sub-zero temps, but we get those occashionally.

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murdermitten · Post by **murdermitten** » Wed Jan 03, 2018 4:21 pm

Thanks all of the assistance! Will putz with it tomorrow and report back.

As for your question feetforbrains, it's having trouble starting anywhere from low 40s F (5C) to well below freezing, where it's really hard to start, probably around 8F when it was most difficult (-13C).

The goal is to get it to start with little or no difference in turn over time regardless of temp, and while that may be a dream, I need to know beyond a shadow of a doubt that I'll be able to get it started as I take the van up to the mountains, often camping overnight even in winter.

sk66 · Post by **sk66** » Thu Jan 04, 2018 9:25 am

IME all diesels are hard to start when the temps get down below 20* (-5c) or so w/o a block heater or something... (I haven't owned a modern diesel).

Yesterday was the first time mine wouldn't start (10*)... well, it might have but I didn't really need it to so I waited for it to warm up a bit later. But it's been hard to start most days with the bad cold snap we've been having last couple of weeks (0-20*f). I don't think my battery is in the best of condition as it doesn't crank easy/fast when cold like this.

I'm thinking of installing a fuel filter pre-heater, and maybe a lighter min spec oil at the next change (I've got 15-40 in it now). The pre-heater can run off the battery for a few minutes and should make starting easier w/ less requirement for glow... but a good quality battery will be an absolute necessity.

feetforbrains · Post by **feetforbrains** » Thu Jan 04, 2018 10:36 am

murdermitten wrote:The goal is to get it to start with little or no difference in turn over time regardless of temp, and while that may be a dream, I need to know beyond a shadow of a doubt that I'll be able to get it started as I take the van up to the mountains, often camping overnight even in winter.

I hear ya, I've got smoky starts in upper 30s. Some of that is the humidity, but some of it is likely poor compression with cold cylinders.

So fiddle, fiddle hard.

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murdermitten · Post by **murdermitten** » Thu Jan 04, 2018 10:23 pm

Okay, so didn't get to much tonight but I can show you guys a few things.

It appears my mechanic wired the button correctly, as the wire is running to the 6V solenoid. The negative wire runs to the fusebox at the firewall near the steering column. I didn't dig much further there.

: wiring2.jpg (103.51 KiB) Viewed 8004 times

: wiring1.jpg (56.45 KiB) Viewed 8004 times

Even after running the engine for a while (read: drive 8 miles home) after a hard start I tried the fuel pump primer one more time, it freely pumps up and down but no fuel comes out and it makes an air sound like it is not actually pumping....thinking this may be the culprit, though I'll get into glow plugs this weekend.

On that note reading through this forum has convinced me to buy OEM plugs, I do have these in the meantime though, has anyone used them?

: 6V.jpg (134.82 KiB) Viewed 8004 times

Thanks again guys

Shaun Van Ramen · Post by **Shaun Van Ramen** » Fri Jan 05, 2018 10:04 am

For what it's worth..

My L300 is always hard to start in temps below 0c. In -10c it takes probably close to a dozen or more attempts before she fires and wants to run. I assume it's from just being really cold. And it has always smoked on initial start-up (warm or cold).

I recently had "No click" issues with my GP relays. Turns out my ECU was fried. Instead of the usual manual bypass, I spent the $100 to have my ECU fixed.
So my thought is that "Hard to start in the cold" is a price we pay for having diesels.

sk66 · Post by **sk66** » Fri Jan 05, 2018 10:32 am

I honestly doubt the prime pump is letting air into the system even though it is bad, but maybe.

The way you are currently set up you should hold the button for about 6 seconds (applying 12v) and then attempt the start. After/during start you may need to push the button *momentarily* to keep things going smoothly... this is where the system would normally switch over to a more sustained 6v glow cycle, but you can't do that.

The problem with manually applying 12v to 6v plugs is that it's easy to burn them out and you have no way of monitoring them. If you are running a manual switch only, I would probably switch to 12v glow plugs. You can still burn them out, but it's a lot less likely.
IDK anything about those plugs, but a quick search shows them as 6.2v and compatible. With a manual glow system there isn't any concern about compatibility requiring OEM plugs... that's about getting the ECU to work correctly.

Post by **Growlerbearnz** » Fri Jan 05, 2018 2:17 pm

I would try the jumper lead to the bus bar test, and see if anything changes.

The CP06 glow plugs will work fine with your 12V manual switch, but they may not be compatible with the ECU. If you reinstall the ECU you'll probably need to switch to Mitsubishi/Hyundai MD092392 or NGK 2161 (or let us know if those plugs also work).

sk66 · Post by **sk66** » Fri Jan 05, 2018 3:16 pm

I'm running the Hyundai MD092392 plugs with the ECU... seems to work fine and they were a lot cheaper.