L400 - engine right off - possibly glow plug fault

[lopar]

I have put little bits of info in other posts about what has turned out to be a engine right off.... small recap first.

short version: just over a month ago on the highway, not under load.......... big puff of smoke (mostly white) and sounded/felt like I lost a cylinder and pretty much all signs of a head gasket or cracked head. Off the road and stopped immediately, no leaks, all fluids looked good, no bubbles/smells and all that good stuff.

Head came off about a week ago, sorry no pics..... but the number two piston and head insert all marred up, cylinder wall scraped and the lip of the precombustion chamber broken off. Number 3 precombustion chamber lip is cracked and looks like it would break off soon. As noted in another post, the glow plug can never hit the piston, there is a pre-combustion chamber where the tip is located.

UNLESS a tip breaks off or something like what happened to mine.

wow.jpg (122.75 KiB) Viewed 4018 times

glow plugs are, left to right, 1,2,3,4 ...... these were installed new about 1.5 months before the incident.

Speculation at this point....... the number 2 and 3 have obviously lost their tips, possibly overheating? number 4 looks like it is starting to burn up or became damaged and number one looks as good as new.

Why, some would overheat and other one not overheat is beyond me, common ground common power all cleaned up nicely.

In the end, I have a new (used) engine going in next week...... $12500 for my Delica, $1200 to replace coolant system, $5500 "ish" for blown engine, getting main seals and such done while the engine is out. expecting about another $1000 at least to fix up a bad lift and get aligned. $1000 in misc, oil catch, cold air couple other toys..... expensive toy.

Comments/thoughts/conerns?

couple other things that i have found while researching:

just abvice and yes, I will say "i told you so"
1. 4m40 heads are weak and prone to cracking..... make sure that you replace coolant system when you get one, do not just flush, replace

2. If you replace the head gasket, there are 4 different gaskets, thicknesses, available, Mitsubishi seems to be specific about this thickness and it is identified by notches on the end, 1,2,3,4. Do not know if this is a diesel thing or not, the thicknesses are not a lot different.

3. 1994-1995 (at least) - the valve/rocker cover breather line allows too much oil to escape into the intake side, this itself will not damage the engine, but reduce performance on the intake side..... add an oil catch system.... other thought, has anyone tried adding a PVC valve?

Cheers

[lopar]

Some more research and thought............ this did happen around/after end summer temperature dip...... searching out, could be a fault of glow plug circuit and or temperature sensor...... short version, plugs on too long during the after glow period (after start up)...... think I might rig up a circuit to max out the after glow cycle to <1 min.

[thedjjack]

Sorry to hear.

What make are the plugs?

From my 1.6L VW days I found all plugs not to be equal.

I would use a tester to see how long the plugs cycle for.

I would add a light to the dash that lights when the plugs cycle and maybe a disconnect switch (you could use a wireless security battery disconnect like the one that Canadian Tire sales or boat/racing car battery disconnect switch (lots of amps)). Or you should be able to remove input power to the controller to shut them down.

I have thought about since I often forget to roll the power windows when I park and end up with the plugs running at the same time as I am trying to roll the windows. When I wired my Mercedes Diesel powered Jeep I could turn off the glow plugs. Handy.

New motor or rebuild?

[lopar]

I would add a light to the dash that lights when the plugs cycle and maybe a disconnect switch (you could use a wireless security battery disconnect like the one that Canadian Tire sales or boat/racing car battery disconnect switch (lots of amps)). Or you should be able to remove input power to the controller to shut them down.

x2

already in works......... fancy(heavy amp) stuff not necessary, just need to interrupt the control voltage at the relay, not the heavy amp side directly to the glow plugs. Just putting a little led in a switch panel I am making for below my single din deck in dash.

If I have time, want to put several makes of plugs in old head and burn them up, time them and check temps..... IF i have time
Would end the glow plug debate quality once and for all
Cheers

[thedjjack]

did the glow plugs hit on the pre-combustion chambers and crack from being to long?

Not sure what the chamber looks like on that motor.

[lopar]

did the glow plugs hit on the pre-combustion chambers and crack from being to long?

99.99999999999999% sure that is not the case. But hoping to rip apart the paper weight (head) and look at stuff like that, pressumably all chambers the same depth and such, so still back to why 2,3 all f'ed up with 4 on the way out. Hopefully get a chance next weekend to take a closer looky at the head.

[tonydca]

Sorry to hear.

What make are the plugs?

From my 1.6L VW days I found all plugs not to be equal.

I would use a tester to see how long the plugs cycle for.

And could you check on the side of the plugs near the widest point (outisde of the actual head); it might have a voltage rating stamped on them.

I think they make plugs for 6V, 11-12V, and 24V supply voltages; if yours are 6V plugs, they will be way too low resistance and run way too hot. Vice-versa for 24V, so not likely to be the case.

FWIW, I for one appreciate you putting the effort into laying out the post-mortem data, which has come by you at great expense. This is good stuff to know, so karma points for you!

[lopar]

it might have a voltage rating stamped on them.

11V - these are plugs that I installed at the beginning of August....... due to the lengthy afterglow period post start, I would be surprised if 6V rated plugs would last much past a week.

FWIW, I for one appreciate you putting the effort into laying out the post-mortem data, which has come by you at great expense.

cheers! and a general caution to all, especially for the L400s, as I have found........ there is lots of good information and most people mean well on this forum. But my unfortunate experience has lead to mega research and like it or not, I would give this forum maybe 40% for "accurately" covering issues. Manly because we simply have not yet acquired the experience. Delica UK is an excellent source, as well as others, for finding more experienced based problems and solutions. Like any forum, they are subjective and at the mercy of those that post....... "reader beware"

[luckydad]

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