When Cold is Tool Cold For a Diesel to Start? (1 Viewer)

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Had the diesel Land Cruiser in this a case a KZJ78 have a no start after sitting out in cold yesterday at work. Average temp was 5 degrees F. I am not surprised it didn't start, but I am also seeing in this forum that people are starting down in the negatives. I understand there are several factors here that are allowing that, and I am trying to determine what my next steps are for this truck even if that is it stays in the garage when it is below a certain temperature and a different truck is taken. Or is it time to load up the shopping cart and get to adding parts. Additionally, I understand this might be a service/maintance issue and will run through some tests once the truck is back at the house.

Information I am after.
- Engine Model
- What is the coldest you rely on it starting?
- Are you running a some kind of plug-in heater?
- If yes for how long before starting?
- Are you running a diesel heater like a Webasto or Espar?
- Is you truck equipped with a cold spec package from the factory?
- Are you treating your fuel more than how it is treated from the fuel station?
 
My old 1990hdj81 has started at -36C just on glowplugs and that delicious 24 volt starter.
Mind you, you need to cycle the glow plugs and add some fuel via the pedal.
We ran many, many 1hz's that start well to -30, after that some need help.
Once again, cycle the glow plugs, and, you need to SEE/Smell some fuel.
Have a HD-FT which uses a glow screen, starts ok ish, but has a Bluetooth Webasto as this runs nearly every day.
-31C here this morning.
You have to have the best batteries possible in winter.
A convection heater is superb if you have hydro. If your away from support carry ether or Brakekleen( the type that burns).
You can also pour hot water over the head, and light a tended fire. Shovel snow around the bottom to trap heat...be patient.
If you live on a hill, use gravity to get that engine turning.
During the day park with the engine/windshield into the sun, do not dismiss the benefit of passive solar heating.
 
My old 1990hdj81 has started at -36C just on glowplugs and that delicious 24 volt starter.
Mind you, you need to cycle the glow plugs and add some fuel via the pedal.
We ran many, many 1hz's that start well to -30, after that some need help.
Once again, cycle the glow plugs, and, you need to SEE/Smell some fuel.
Have a HD-FT which uses a glow screen, starts ok ish, but has a Bluetooth Webasto as this runs nearly every day.
-31C here this morning.
You have to have the best batteries possible in winter.
A convection heater is superb if you have hydro. If your away from support carry ether or Brakekleen( the type that burns).
You can also pour hot water over the head, and light a tended fire. Shovel snow around the bottom to trap heat...be patient.
If you live on a hill, use gravity to get that engine turning.
During the day park with the engine/windshield into the sun, do not dismiss the benefit of passive solar heating.
You aren't the only person I have seen give the 24 volt starter high praise.

Everything else makes sense.

With the Webasto style heaters do those get run for an hour before starting or are those running all night? Pardon my lack of knowledge it getting this cold is a once or twice year experience not a life style.
 
I do not have a lot of experience with a wide variety of diesels. Almost none with the Toyota engines.

Indirect injection Gm 6.2 and 6.5s with glow plugs have always started pretty easily even in sub zero temps so long as there was enough battery to spin them quick enough.

Mercedes 5 cylinder (I forget the nomenclature) with no glow plugs or screens out of Brazillean Banderandie "cruisers"... flat out refuse to start when it is cold at all. This is without a block heater. that would change things I expect.

The Mercedes 4 cylinder in those rigs does just fine down into the teens. No experience colder than that and no block heater comparisons here either.

The only 3B I ever dealt with in cold weather had a block heater on it so I am not sure what a a really cold start would have been like but with the heater plugged in it would start in sub zero temps just fine.

This was all in plain old fuel, not always even winter blends.

No personal experience with newer Toyota diesels.

Does your engine now have glowplugs/screens? if the battery is up to spinning the engine at a decent speed it should start with little issue at those temps.

Again, I am not really a diesel guy (I own, drive and maintain several older GM 6.2s and 6.5s, but I am not really a diesel guy), but *my* experience and understanding is that while a gas engine can often kick off even when it is just barely cranking, the diesel simply will not fire below a certain cranking rpm. It needs the compression heat, glow plugs or not. So good powerful battery (batteries) make a lot of difference.

A simple electric freeze plug heater will make a world of difference in your cold morning starts. At 5F you should start like it is a summer day if you are plugged in for a couple of hours (longer in really cold temps). If it is gonna be -20... just leave it plugged in all night.


Mark...
 
You aren't the only person I have seen give the 24 volt starter high praise.

Everything else makes sense.

With the Webasto style heaters do those get run for an hour before starting or are those running all night? Pardon my lack of knowledge it getting this cold is a once or twice year experience not a life style.
Mine is programmable via a Bluetooth App.
Others can be temperature driven.
 
My 1HZ started without issue this morning at -1 degree.....so did my cummins

Thats the coldest yet for the 1HZ

I've never had a diesel that didnt start......coldest temps I have seen is -26

And none of these have a block/pan heater

Edit.....24v 1HZ is pretty amazing and all of the above ALWAYS get Power Service treatment to fuel
 
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BTW
A cold snap can and will degrade your battery by 50%
Matter of fact mine were down to 17 percent this morning...charging at over 14volts.
I will be purchasing two of the biggest and deepest batteries possible. This is one thing I never mess with especially because I am normally out in the woods and there is no cell coverage in case you need help.
The hill I'm skiing today registered-42C overnight. I'm letting it warm up a bit, and will prepare a few items just in case.

Screenshot_20250121_080855_Windy.jpg
 
@Mark W yes truck has glow plugs. Less than a year on them. Doesn’t mean something else hasn’t gone bad in that system. Probably will do some confirmation of that system working this weekend.

@jayp2 thanks for that data point.

@Squash good to know batteries will loose that much in a cold snap. The truck is a dual factory 12 volt system with batteries that are under 2 years old, but worth checking.

I am leaning towards there is one or several systems not at 100%. Troubleshooting is a little funny because I need to be cold to replicate the situation and test.
 
@Mark W yes truck has glow plugs. Less than a year on them. Doesn’t mean something else hasn’t gone bad in that system. Probably will do some confirmation of that system working this weekend.

@jayp2 thanks for that data point.

@Squash good to know batteries will loose that much in a cold snap. The truck is a dual factory 12 volt system with batteries that are under 2 years old, but worth checking.

I am leaning towards there is one or several systems not at 100%. Troubleshooting is a little funny because I need to be cold to replicate the situation and test.
What are you hearing for turnover of the engine?

If rpm's that the battery/starter "system" is able to create is very slow/limited that will contribute to issues

Weight of oil could be a contributing factor as well.....I have 5 weight oil in everything (some are 5/30 others are 5/40)....molassis in the oil pan doesnt help with starter rpm's

Similarly if you arent treating fuel then you could have delivery issues.....once fuel gels in a filter its pretty much done.....change the filter.....you may need to look at state of diesel in the tank/lines

Beyond that its just a question of whether or not the grid heater/glow plugs are doing their job to get started

EDIT: Air intake can be an issue too.....you wouldnt be the first one to see a mouse nest in the air intake/filter system.....all my vehicles get oil undercoated every year and some peppermint oil is in that mix......rodents hate it
 
What are you hearing for turnover of the engine?

If rpm's that the battery/starter "system" is able to create is very slow/limited that will contribute to issues

Weight of oil could be a contributing factor as well.....I have 5 weight oil in everything (some are 5/30 others are 5/40)....molassis in the oil pan doesnt help with starter rpm's

Similarly if you arent treating fuel then you could have delivery issues.....once fuel gels in a filter its pretty much done.....change the filter.....you may need to look at state of diesel in the tank/lines

Beyond that its just a question of whether or not the grid heater/glow plugs are doing their job to get started

EDIT: Air intake can be an issue too.....you wouldnt be the first one to see a mouse nest in the air intake/filter system.....all my vehicles get oil undercoated every year and some peppermint oil is in that mix......rodents hate it
That’s part of the issue, this is the partner in crime’s truck and I was doing the trouble shooting over the phone with her. I could hear what I thought was strong cranking and she said the glow light was cycling like normal. I think that might be the issue. I looked at the graph for that and the timer should be running longer than what is typical for that truck.

Fuel was treated and topped off right before the cold snap as a precaution. I get what you’re saying about the filter. I have spare filter here and if the truck doesn’t start this afternoon I’ll swap a filter and report back.

Looks like I’ll be breaking out the multimeter regardless to verify systems.

Unfortunately, I am familiar with furry rodents causing issues, but a good reminder to double check the basics.
 
I have an old IDI tractor that needs it's engine rebuilt in a bad way, has about half the of the compression it's supposed to have. I use it plow snow in the winter. treating the fuel with power service really helps in a big way with how easy it starts. Not just because it's not gelling but also it seems to help it ignite better. I can still start that thing at 5 without starter fluid with alot of cranking. I have had untreated fuel gel in my 99 Mercedes e300 before at about 5 degrees. Another time I started at -5 with treated fuel and it started right away just like it was warm out, no problem. that Engine is also iDi with glow plugs like the 1hz about 200k miles. Not sure of the history of your truck but it could be worth checking compression if everything else checks out first.
 
No need to echo all the good stuff above, but I will add that a tired injection pump will not start as well as a freshly rebuilt pump and injectors. Makes an amazing difference.

Concerning changing the filter, if the fuel is not gelled, it’s not gelled. I would greatly hesitate to pull the filter off anything in cold temperatures, without warming it up at first. Of course, engine/fuel system design has a lot to do with hard starting and purging the air after a filter change. A Ford 7.3 or an older Deere are a complete pain in the butt when problems do happen. All my Cummins and newer Mack’s have started fantastically over the years.
Sadly still waiting to get experience with a Toyota diesel, maybe one day.
 
Cold snaps call out the diesel engines that have been getting by with low compression. Oh and for those that have good compression and non winter blend / treated fuel, you can’t pump jello. In a pinch, if you have enough ground clearance to slide a torpedo heater with a right angle piece of stovepipe on the front under the oil pan, you just created warm weather conditions for your weak ass diesel. Suck-squeeze-bang-blow!
 
Here's my 3b Troopy a few years ago. Got down to +1 F during the night. I went out after lunch and started it. It was +12 F outside.
No fuel additives. Did not plug in the block heater.
It has a 24v starter and that does make a difference.

 
Alrighty, as per usual the MUD community is an overwhelming wealth of knowledge. Thank you all for the help and insight. I just got back after getting eyes on the truck for the first time since it's no start and the truck is now parked back in its normal place at the house.

Solution: Truck lost prime. The filter was loose and needed about an 1/8 of a turn to snug up and then the hand pump took about 10 pumps to firm up. After that I did a quick check on batteries and they were reading fine and the truck fired up with gusto! I loaded tools, followed it up home, and then promptly fired up the parts cannon. I have a filter housing on its way. At this point I've read of enough of these failing they seem to PM item after a certain age. I want to know why the filter is loosening, but for now I'll paint pen it so I can visually check it and make sure it isn't backing off in the future. The housing was damp when I checked it, and it was around 35F outside. My working guess is there was a minor sealing issue which got worse when everything got cold and shrunk. Plus if there was any water in that filter that didn't help anything either.

Future Immediate Work:
With the new filter housing, I'll of course do a new filter, along with fuel lines. After that I'll put together a kit with a spare filter, filter wrench, a printed copy of instructions on how to swap the filter that'll live in the truck.

Future Work:
-Test glow system. I don't think anything is wrong here, but it is peace of mind. I also much prefer doing testing work on my time not when a truck is down.
- Compression test. As @TheBussman and @fjc-man pointed out compression matters on these and cold weather does show when an engine is unhealthy. I need to make sure I have the right adapter for this truck, and then do a compression test.
-Injection pump refresh and either new or rebuilt injectors. @Ditcherman pointed these out and it makes sense if these aren't operating at their full potential they are gonna make running in the cold harder. I am casually looking for a spare pump so I can get that refreshed before hand so I don't have the truck down for so long. I need to see what the usual rebuild/replace interval is for those parts. Also I think time is a factor that shouldn't be ignored entirely and I shouldn't base it entirely on mileage.

Future Future Work:
- Block Heater or Recirculating pump. Leaning towards a recirculating pump. I get this wouldn't have solved today's issue, but today won't be the last cold day this truck sees either.
- A Webasto or Espar seem like a nice feature in the future if the truck is getting left out for long times and it isn't making it home for the night. A bit overkill at the moment, but I also like being able to consistently rely on a truck especially when it's cold.

If anyone else has data points for how cold they are starting their engines successfully I would love to hear it because it was helpful to know these trucks should start without issue even when it is brisk to say the least.
 
Great to hear it was as simple as a loose filter. I'll throw out a few more data points in terms of cold starting:
- Both my 1997 VW TDI's started unassisted at -15/-18ºF with 2-4 glows, one had about 240k miles and the other about 210k.
- My parent's first VW TDI started at -18ºF unassisted, their current one struggles anywhere below freezing (2004 with ~280k miles). Definitely something not working right to cause the hard starting.
- My 3L powered Hilux started unassisted at 9ºF on one glow, no smoke and smooth idle. It had 115k km.
- My 2L-TE started easily on one glow at single digit temperatures until the head cracked. It had 112k km.
- My Mercedes OM617 turbo struggled below about 20ºF, it had a freeze plug heater and an oil pan heater that I used when possible. Unknown miles. I got stranded with it once after a night out at -20ºF, reviving it the next day is a whole story by itself.
- My Mercedes OM617 NA didn't like starting at all, especially in the cold, until I found that the starter was completely shot. Upgraded glow plugs and a new starter brought some life back to it, though I never started it in wintertime conditions it would happily fire up at freezing temperatures.
- The two Cummins in the family (12-valve and 24-valve) both start down into the single digits, haven't tried starting them unassisted at temperatures any colder than that. The 12v has ~400k miles and the 24v has 230k miles.
- My older brother's 2001 VW TDI will start (begrudgingly) into the low teens. It has 394k miles.
- My younger brother's 2001 VW TDI doesn't like to start when it is below about 25ºF, it has a broken glow plug and ~240k miles.
- My TDI Prado started once at -20ºF with assistance from a battery charger, it took several minutes of cumulative cranking to get it to finally fire and stay running. Now that I've installed a Webasto I usually run it when temperatures drop below about 25ºF. Instant heat in the cabin is awfully nice too.
- My brother's 1HD-T started at -18ºF unassisted on a couple of glows. It had 325k km at the time. That 24-volt starting system really is a wonderful thing.
 
Had the diesel Land Cruiser in this a case a KZJ78 have a no start after sitting out in cold yesterday at work. Average temp was 5 degrees F. I am not surprised it didn't start, but I am also seeing in this forum that people are starting down in the negatives. I understand there are several factors here that are allowing that, and I am trying to determine what my next steps are for this truck even if that is it stays in the garage when it is below a certain temperature and a different truck is taken. Or is it time to load up the shopping cart and get to adding parts. Additionally, I understand this might be a service/maintance issue and will run through some tests once the truck is back at the house.

Information I am after.
- Engine Model
- What is the coldest you rely on it starting?
- Are you running a some kind of plug-in heater?
- If yes for how long before starting?
- Are you running a diesel heater like a Webasto or Espar?
- Is you truck equipped with a cold spec package from the factory?
- Are you treating your fuel more than how it is treated from the fuel station?

1hdt
-10 to -15 seems reasonable
no
no
no
no
i treat fuel in the cold to keep it from gelling

I have started it down to about 5* and it kicks right over. It'll idle rough for a second or two.
 
If all electrical components are sound as mentioned above, then suspect fuel.
Cold will make holding a vaccum in the fuel delivery system tougher because rubber becomes stiff, and any defect will allow air into the lines/filter etc.
YOU need to smell and or see fuel at the exhaust in what I call a cold snap(-30C/-20F)
or colder.
Extra glow cycles, add fuel when cranking with the pedal or add fuel conditioner if you suspect icing of your fuel if everything else is in good shape.
No fuel=No start.
If she is chugging you can help by holding the key a little longer...the chugging and starter can help each other.
Only-28C here today and both the HZJ75 and Hdj80 fire up.
 
I’m gonna assume everyone here knows NO ETHER in a glow plug or heater system, right?
But mentioning it in case someone stumbles along later on…
That being said, I have a couple of 7.3’s that get started with ether if it’s below 40. There’s a method to the madness where you let it crank and then cycle the glow plugs to make sure they’re cool but it’s not for the faint of heart or if you can’t afford a new engine.
 
Different perspective and thought i would share. I have had several diesels ( 2H, w123, 7.3) all suffered from cold start issues, even ones with 24v starters. 24v systems were worse. Even using new batteries with same build date, they fought each other and drained. Anytime the temps dipped my worry meter went up. Getting to and from work was getting the to be a chore. When it came to building a cruiser for trips, i thought hard about it. Love diesels for most reasons folks do. The cold start issues had me think hard. I did not want to get stuck somewhere due to the above reasons. I am not planning any trips to Alaska in the winter where it stresses out any platform. I decided to stay gasoline and LS. Simplifies alot of things for me. I know this is not an engine swap thread, but thought I would share.
 

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