Delica Canada | Mitsubishi Van Club

Delica L300 new cylinder head and cooling mod.

It seems that there is a lot of L300s with failing cracked/ warped  cylinder heads, mine just happens to be one of them at 190,000 kms .
After a lot of searching I found one here for under $700.00 CND shipped UPS complete with a gasket set and new head bolts .

http://www.ebay.co.uk/itm/Mitsubishi-pa ... AQ:GB:1123

While waiting for the head to arrive I started prepping for the swap, with new injection pump seals, crank/cam seals timing belts etc. etc.
All the while reaserching  as to why these heads fail in the first place it seems that the cooling system and not the aluminum or poorly designed cylinder  head is the problem.
The 20 year old + viscous radiator fan coupling is a major culprit they are designed to spin fee at cool temperatures and lockup when the hot radiator temperature hits the thermostatic plate in front of it causing it to expand and engage a tiny valve which allows the silicon oil to flow and lock up the fan clutch. This is a genius design, working only when it has to and freeing up probably around 10 HP when it is not.  The easiest way to test if it is working properly or at all is to run your engine until hot, shut it down and watch that the fan comes to a quick stop, if it continues to spin it has lost its ability to cool the radiator. Here are a couple of good reads about it.

http://www.4x4wire.com/forums/showflat. ... er=1223543

http://www.mitsubishi-forums.com/t41959 ... ce-fan.htm

The radiator itself is another major problem more than likely not properly serviced  for 15 years as these vehicle are treated as disposable items in  Japan . It is blocked by the AC radiator in front of it and an electric fan  in front of that, and some more hot transmission fluid inside of it , is this the same guy who designed  with the alternator tentioner ? 

To allow for better cooling and to protect my new investment I decided to scrap the AC  but keep the electric fan and frame for additional cooling  ( easy drill out the 4 pop rivets and remove the fan bolts and the core slides right out) . I am planning to wire it to a temp. switch with a manual override for climbing hills and low speed 4X4 .  Any comments on this mod would be much appreciated and welcome especially the  temp. switch wiring.

During this repair it has occurred to me that the AC condenser would make a great  donor for the transmission radiator, much bigger, built-in fan  and would free up the engine rad for even better engine cooling.
My concerns regarding this mod are : 
Proper decontamination, material compatibility, flow rate/ pressure restriction, etc.
This could be the L300 mod/ cylinder head saver, cheers, looking forward to any posts only relating to this mod, thanks.

While no doubt there can be cooling issues in these old vehicles, I think you're barking up the wrong tree. If you do some more research, you find that heavily loading any turbo diesel can result in cracked heads; even a big, powerful V8 if used to tow hard and has an aluminum head, can have this problem. Seems that with the turbo on, you can actually overwork a diesel. Trying to push our heavy vans up mountains can certainly fall into that category. If you research EGT gauges and their applications, you'll find that this a common issue.
I say this because from my own experience and the experience of others, you can blow the head without ever overheating the cooling system. Most of the time when these things go, the cooling system temperature was in the normal range.

I do have a Pyrometer and monitor those exhaust temps. comming through the turbo. I still think the cooling system can be much improved and that is why I decided to submit this post.

I think the when the rad is little low on fluid you have air pockets in the head...

Next you have people running air conditioning all summer, automatic added heat (you can over cool an automatic if you do not let the radiator heat the transmission fluid (this is why automatics are not just on there own radiators)).

now spike your EGT on a long climb and you can fail the head or cold motor and extreme EGT before warmed up.

L300 is a brick, with big tires, 4x4 axles, and 5,000lbs which is a big rig to push around with a little motor...

If my head goes 4m40 would be a nice motor (I know everyone says it will not fit (I got a grinder and a welder) or Mercedes OM617

But 200,000km+ on a 24 year old Delica (but I keep the cooling system up and EGT down)... I agree increased cooling system is not a bad idea

The failure of the viscous fan clutch is one of the big causes of head cracking in Hilux Surfs so I think its a good assumption it is important on the Delica as well. Silicone oil just aint what she used to be after 15+ years.

One trick on the Surf I have used is to use a higher wt silicone for an earlier engagement. It is also typically cheaper than oem which is also a plus. Best source is from hobby shops...shock oil for rc cars, comes in many wts. Oem on the Hilux was ~3000wt' I am using 15000wt.

The head arrived yesterday morning, got it on and just came back from Alice Lake, so far so good .
here are a couple of pictures .

bling

all done

You make it look so easy Nice job. You just saved yourself over 4 grand!

While extra cooling can help, my still believe it is mostly on how you operate it. This engine has been used extensively in the industrial sector in skid steer's, gensets, water pumps, and many other applications, and is not known for cracking heads. They are known to run for 10,000hrs plus with regular maintenance. And that is 10,000hrs under full load. In all these applications, the engine is started, warmed up, and then put to work, and run at 3500rpm, all day long. When the load is removed, the engine is cooled down, and then shut off. These engines are not made to be lugged. If you are working it, drop a gear and keep your rpms up, the engine needs to breath. Lugging it generates extreme temperatures in the cylinder, and the coolant simply can't take the heat away fast enough, no matter how big your rad is. Not letting the engine warm up or cool down properly also contributes greatly to the cracking of heads. Rapid expansion and contraction of the aluminum head stresses and fatigues the aluminum, and over time, it just can't take any more. Unfortunately, some of this damage may have been done by the previous owners, long before the vehicle came here. So you can do everything right, and still have this problem, because the damage has already been done. Or you may get one that was treated properly, and you'll be able to abuse it for the next 150,000km, or treat it right and have it last the lifetime of the vehicle. Food for thought.

Jason

I agree with the above. When I showed my old rad to a rad shop to see if it could be refurbished, he was very surprised that it was for a 2.5 diesel, and remarked that it could be used to cool a big V8; it has a much greater density of fins and channels than most radiators for engines twice it's size. I suppose that's why the coolant rarely gets above the 1/4 mark. That capacity makes sense because where the rad is located means much less airflow than in typical front mounted ones.

SunshineCoastMark wrote:Delica L300 new cylinder head and cooling mod.

To allow for better cooling and to protect my new investment I decided to scrap the AC  but keep the electric fan and frame for additional cooling  ( easy drill out the 4 pop rivets and remove the fan bolts and the core slides right out) . I am planning to wire it to a temp. switch with a manual override for climbing hills and low speed 4X4 .  Any comments on this mod would be much appreciated and welcome especially the  temp. switch wiring.

HI wondering if you ever did the above mod with removing the AC Rad and keeping the electric fan on a temp. switch and a manual overide? I'm thinking of doing the same and was wondering how it worked out for you.

Cheers.

A few years ago I was having cooling issues with my previous L300 doing the coq climbs in summer. I ran a jumper from the A/C fan to a coolant switch fixed at 180.(ebay) The problem I had was it was constantly cutting off and on and did not seem to "assist" my clutch fan cooling to any large degree. Ended up plumbing in a secondary rad on a valve which added to the ccoling capacity. The problem with that, was it allowed the engine to run too cool when not under load, (coming down from toll we froze our asses) and since it was a manual valve accessible from the front - it was a PITA
In the end, turned out to be a restriction in the head itself causing the heat issues.

Hi, I did remove the AC rad, fan and the viscous factory fan and replaced it with an aftermarket electric fan that has its own electric thermostat and a thermocouple that I installed right inside the upper rad hose, its been working great. I have found that the AC condenser is not a good donor for the transmission cooler as it would restrict the flow too much so just scrapped it.

fan 1