Low boost + high EGT

[JRM21]

Hey all,

I've been having some issues lately with my Delica (1994 l300, 2.5TD), I wanted to see if anyone here had any thoughts.

First off, the turbo has been pretty lackluster. I used to be able to get 14-15 psi of boost, but right now it won't go past 9 psi. I checked pretty thoroughly and couldn't find any leaks. I feel like maybe the wastegate is opening earlier than normal. Is there any way of adjusting the wastegate to create more boost?

Second problem, the EGTs have been high lately. This started at the same time as the problem with the turbo, and it seemed like a pretty obvious correlation, but at the time the increase was more or less negligible. Lately, they've been higher and it's starting to become a concern. Normally when cruising on the highway the EGTs would sit at around 600-700 degrees (F), lately that has gone up to 800-900. Hills have become a nightmare, I have to drive below 60 km/h to keep the EGTs under 100. All of this has also been causing some slight overheating. The temperature gauge now normally sits at a quarter, and will go up over half on a hill. I've also been losing coolant.

Has anyone experienced similar symptoms? Could the high EGTs be caused by the lack of boost (ie changes in air-fuel ratio), or should I be looking elsewhere. Thanks guys!

[ChuckBlack]

Hey I've got a few questions for you old friend!

What type of coolant are you using?
Have you replaced you thermostat lately?
Have you had your turbo tested or replaced lately?
How clean is your air filter?
Have you checked all turbo boost connections for potential leaks?
Have you disconnected your boost actuator and manually worked the gate?
Have you disconnected you turbo air inlet and wiggled the finns and checked end play?
How accurate is you boost gauge?

I've got a L300 4D56 1993,
Cheers...

[Growlerbearnz]

High EGTs can absolutely be caused by too much fuel, not enough boost. Low boost pressure makes the charge burn later and for longer, meaning it's hotter when it goes past the exhaust valve.

I'd check the things Chuck suggests, and if everything appears to be in good condition then try shortening the wastegate actuator rod (or spacing the actuator up with a couple of washers). If it's simply a case of your wastegate actuator getting lazy, that should increase your boost again. If it doesn't, then you've got a boost leak. Curious that you used to make 15psi- have you disabled the overboost blowoff valve?

[ChuckBlack]

Oh by the way how long ago have you have your timing checked? And have you your timing belt replaced lately? I also suspect that you're running too rich... Excessive fuel, bad timing,bad injectors....

[FalcoColumbarius]

I have a question for you: When was the last time you changed your air filter element?

Before you tear the intake manifold apart I'd check and replace the filter. I would advise against Fram as the paper is too thick and behaves like a dirty filter to start with. I like Sakura.

Falco.

[JRM21]

Thanks for the replies guys,

The coolant I'm using is pretty cheap. It's basically just water mixed with an anti-corrosion agent. I'm currently living in Guatemala, and since it never gets close to freezing here that's pretty much all you can find. I have heard that straight water is best for transferring heat, but it occurs to me that proper anti-freeze usually increases the boiling point as well. Could be that the coolant is just boiling off.

Haven't checked the thermostat yet, that's next on my list. The air filter is relatively new but I will replace it anyways.

I haven't had the turbo checked, but I took off the inlet and it spins freely with no play whatsoever. I tried my best to check for leaks, but couldn't find anything. The lines going to the fuel pump, wastegate actuator, and boost guage are definitely fine, as is the connection from the turbo to the intake manifold, but it's kind of hard to check the seal on the intake manifold itself. The wastegate works fine, and the rod isn't seized up. As far as I can tell the boost gauge is functioning properly based on rudimentary tests with a compressor. I haven't touched the blowoff valve, and it used to go off if I was climbing a hill at high rpms. Now it never goes off.

The timing belt was replaced about 3000km ago, but I checked and all the timing marks line up. If the belt stretched or lost tension but didn't skip a tooth would that still affect the fuel pump timing? It definitely seems like it's running rich, and I was thinking about retarding the timing a notch or two but I'm slightly concerned about blowing up the engine ... Has anyone tried this before?

With the wastegate actuator, I have a feeling that the actuator rod was partially seized when I bought it, so the wastegate wasn't opening properly which would have caused the abnormally high boost. Then at some point the rod might have freed itself up on its own and now the wastegate opens properly, which causes the turbo to create a "normal" amount of boost. Does that sound at all plausible? I will try the washer trick and see if increasing the boost will lower the EGTs. It will be a few days though because I just pulled the rad to give it a good cleaning.

[FalcoColumbarius]

One thing about the coolant, make sure you get the right one. It's not just about anti freeze, &c., it also should have anti-corrosive properties to stop any galvanic reaction transferred through the water between the cast iron block and the aluminium head. If you use a coolant that is meant for a different alloy head it could work against your system and eat your head.

Falco.

[JRM21]

... well that doesn't sound awesome. I'll look into it.

[ChuckBlack]

Yea implosion and cavitation are Rudolf Diesel's worse nightmare!!! You should definitely stay away from any water base coolant and jump to an organic ELC! Better heat transfer, no more implosions surrounding the water jackets and an overall heat efficiency! Now are you saying that your turbo has no end play what so ever? That's odd! You should have at least .002" end play! Allowing side play between the seals! Axial play isn't good but should check again for end play! check that you don't have some dead bird inside your air intake piping! Seen it happen before with a dead rats ness!

[FalcoColumbarius]

... well that doesn't sound awesome. I'll look into it.

A lot of guys use Mopar, I've been using Hepu G11. I run my mixture at 40% coolant and 60% water, as water does shift more heat. A 50/50 mixture is a bit over kill unless you live in the Arctic ~ I live in the Lower Mainland, where in the outlaying areas it might get to -25 with the wind chill on occasion ~ 40/60 coolant to water is ample, in my opinion.

Falco.

P.S.: I change my coolant out every two years as it does go stale and stops doing it's job. FC.

[JRM21]

So I went to replace the thermostat today and I made a couple of very interesting discoveries today! Not sure if they have anything to do with the problems I've been experiencing, but interesting none the less.

First off, I removed the fan to make getting at the thermostat easier and decided to check the fan clutch by putting it in a vice. It wouldn't budge at all. Great news, right? But also kind of suspicious since it should move a little bit. Then I noticed a bit of black rubber sticking out of the fan clutch where it bolts together. I decided to take it apart and see what was going on inside and found a circular donut of rubber cut out of an inner tube ... I did some research and from what I can tell this is a fairly common method for extending the life of a worn out fan clutch. It purposefully seizes the fan clutch up, so that it's always spinning at the same speed as the engine (instead of easing off at higher RPMs) ... Obviously this will benefit the cooling system at lower RPMs, but will also sap a lot of power at higher RPMs and probably isn't great for the water pump ... Anyone heard of this before? Could it cause the overheating maybe?

Second discovery: no thermostat! Previous owner must have pulled it to increase flow through the rad. So now I'm worried that if I put a new thermostat in, it's going to make the problem even worse! I'm in a pretty warm climate right now and the engine warms up quickly, so it's not like it's completely necessary ... is it? Could the back pressure created by the thermostat possibly be necessary for the cooling system to work properly?

[Growlerbearnz]

It sounds like someone had an overheating problem, and decided to bodge it up rather than fix it properly. If it's getting to a decent temperature even with the fan clutch locked and no thermostat, it suggests your radiator might be clogged.

The thermostat is fairly important in a diesel- if the engine block isn't hot enough it gives you poor combustion which can clog up injectors, soot up the valves and head, and cause high EGTs. I know that in some engines removing the thermostat causes the coolant to bypass some areas of the engine, leading to localised overheating while the temperature gauge says everything is fine. I don't know if that applies to the 4D56 but I wouldn't be risking it.

[JRM21]

I think I might have found the problem for the high EGTs. The pistons on the passenger side brake calliper isn't retracting properly so the brakes have been partially engaged while I've been driving ... which also explains why it's been pulling to the left! The brake pads are pretty bad, but they weren't worn down completely and the rotor seems to be in good shape still.

I know very little about fixing brake callipers. It's a dual piston calliper off of a l400. The pistons extend when the brake pedal is applied, but don't retract fully. Any thoughts? Maybe the seal around the piston.

[Growlerbearnz]

L400 callipers are great, but they need more preventative maintenance than most.

The usual problem is the sliding pins- if they're not lubricated regularly with the correct silicone grease they can rust and stick. Luckily they're very common (fitted to a great many Mitsubishis) and easy to replace. It's a good idea to replace the rubber bushes while you're there.

The piston not retracting will be from dirt or corrosion on the piston, usually from a torn or dislodged dust boot. Behind the dust boot is the piston seal, which is supposed to twist a little when the piston pushes out, when you lift your foot off the brake the seal un-twists and pulls the piston back in. If there's dirt around the seal it won't twist. A quick fix is to lift the caliper away from the brake disc, put a piece of wood between the pistons, and put your foot on the brake so the pistons come out further than they usually would. Watch the pistons as you do it (or do it in small stages) so you don't push them out too far so they fall out! Then push them back in. You might need to repeat it a couple of times, but it should clear the dirt a bit and stop the piston from sticking for now.

That's just the temporary fix though. You'll probably find that the dirt has damaged the piston seal, and it'll start leaking. The correct fix is to disassemble the calliper, clean everything, and replace all the seals. It's a good idea to replace the pistons too. Rebuilding brake callipers isn't hard, you just need to keep everything spotlessly clean and use lots of brake fluid as lubricant when reassembling so you don't damage the new seals.

Here's my list from last time I did it:

Calliper seal kit MB857840 $18 (1 side, includes piston seals, piston dust seals and clips, sliding pin boots, lower pin rubber tip, magical grease)
Calliper pistons MB857837 $41 each (ouch)
Upper sliding pin MB618227 $10.50 each
Lower sliding pin (with the rubber tip) MB618228 $9.50

[JRM21]

Thanks for the excellent advice! I ended up rebuilding both calipers. The drivers side brake was working, but the dust seals were torn so I figured I might as well. I couldn't find new pistons or sliding pins so I cleaned and polished them as best I could. They're working great again now, we'll see how they do after I take her through some mud though.

Unfortunately I haven't had the opportunity to test her out, because now the starter motor won't turn over! The starter relay clicks on when I turn the key and clicks off as soon as I let go, but the starter doesn't make a noise. I'm guessing just a loose connection somewhere, but I can't track it down ... I've actually had this happen a few times before, but it would usually only last a few seconds and the starter would go after I cranked the key a few times. I tightened the alternator belts up pretty good, would overly tight belts keep it from moving? I also pulled the glow plugs to clean up the connections, I doubt that has anything to do with it but you never know.

This little project has become much more productive than I had hoped ... fortunately I've got lots of time!

EDIT: the in-line fuse between the relay and the battery had blown. Good to go now!