Exhaust temperatures

[PeterSchurms]

Has anyone measured the exhaust temperatures? If so, what, where, how is the best method to measure it and what is normal? My exhaust is currently standard.
Pete
95' 3.1TD MU Auto

[geeves]

Why do you want to measure exhaust temp If you mean at the manifold then you need a pyrometer as the temp is in the order of sev thousand deg c At the tailpipe exhaust can still be well over 100deg c even with light running.

[Graham]

I read an article about Diesel engine temps that was written by a shop in South Africa, I think their website ended with a .za code.

Anyway, the meat of the subject was that if you're trying to get performance out of a diesel that the critical thing to monitor is the exhaust temp using an EGT.

If someone is increasing boost and getting serious I think this should be looked into. If I can find the article, I'll post it.

Cheers, Graham.

p.s. I've got no idea what's healthy and critical temps - it's been too long since I read it.

[Graham]

Holy cow, I found the article first go. Gotta love google ;D

4xforum.co.za/articles/diesel.html

It's a good read, definitely recommended, even though it does sound more like a story trying to sell EGTs.

Graham.

[PeterSchurms]

Graham, top article it even describes my problem, but so have other articles and performing those suggestions has not fixed the problem yet. The article sounds like a bit of a sales blurb at first, oh well it looks like Turbo replacement is next on the job on the to do list..

Oleg got me thinking about this a while ago, thats when I installed the Boost gauge. The tubo does not loose boost so I stopped pursuing this as a problem cause.

The temperature on my MU rises (has not been past half way yet though) when driving up a steep hill for over 5 mins under full throttle and the oil pressure drops to 2 at 2000rpm and she becomes sluggish. When I go down the hill the temperature falls and oil pressure rises to normal (3.8 at 2000rpm). The heating problem is worse in summer, especially when I have to turn the heater on when its 40deg outside. It has not always been a problem but its one that is really really annoying me.

I am only curious about measuring exhaust temps just to find out what it would tell me. From the article it looks like a lot. Measuring exhaust temps sounds expensive. So probably not an option.

I have spoken to couple people about this heating problem and have tried the following. After all the changes listed below the problem is not as bad as it was but I just want it fixed.

Jobs done so far:
- Removed and cleaned radiator (it was fine)
- Replaced thermostat
- Replace inhibitor with Nulon Anti-freeze/boil (60/40 mix)
- Replaced fan clutch ($200)
- Installed turbo boost gauge. Cruising @100 - 6psi, Loaded - 10psi (Maxed). It does not loose boost when hot. But I am not sure if the waste gate leaks.
- Serviced Transmission
- Installed Transmission cooler
- Installed turbo timer (not related to heating problem though)

Other jobs I am considering:
1. Replacing turbo - it does have a wind down noise, but does not loose boost.
2. A Dyno tune
3. Replacing exhaust muffler or upgrading to a 2.5 inch system
4. Installing gauge to measure exhaust temp
5. Installing gauge to measure water temp
6. Installing gauge to measure auto oil temp
7. Installing gauge to measure engine oil temp
8. Replacing Auto transmission
9. Installing intercooler
10. Installing a Snorkel (not sure if this will help)
11.

Looks like 1 and 2 will be first off the rank.
Thanks!!

[justin]

Good luck with No1 Pete, I did this 6 months ago, hope you've got nimble fingers. My turbo had a winddown too but that wasn't and shouldn't the reason for changing. It eventually started to sound like the bearings had gone in it, (which was the case), then it was $$$$!'s from then on. J

[PeterSchurms]

Cheers Justin,.
Nimble fingers, tell me about it.... I went to a wreckers tonight to 'grab' a second hand one..... Nightmare! Those 4 little buggers were very, very tight. So tight it stayed there. I've decided, if I am going to change the turbo, its worth doing properly..... This means paying someone else to loose the skin off there knuckles, swear a lot. Also, I've decided to get a new one too.

It will need a dyno tune any way, might as well get it done at the same time.

[Witchdoctor]

Peter having very similar heating problems only just started, very tying as i have replaced the water pump,had the cooling system prof cleaned. the temp rises on any rise under load or just cruising any ideas any one that would be great.

Dave

[PeterSchurms]

Dave, Get a boost gauge installed and take some readings. Do not buy the cheepest one like I did. I think mine has been giving flase readings.

I will be replacing the Turbo after Easter. I'll let you know if that fixes my problem.

Cheers,
Pete

[wayne]

The temperature on my MU rises (has not been past half way yet though) when driving up a steep hill for over 5 mins under full throttle

Peter, I fail to see what the problem is. What you have described is normal. People read too much into gauges, if the needle isn't hitting the red then I don't worry (mine goes to 2/3).
As for the oil pressure it is not the pressure that matters it is the flow rate. Hot oil is thinner and generates less pressure at the oil pump hence the lower reading.
My oil pressure gauge reads either 0 when the engine is stopped or 8 when the motor is running, nothing in between. If it ever reads 0 when running then I'll worry.

Big bore, free flow exhausts should be fitted before turning up turbo boost to allow the extra heat generated to escape.

W.

[Harry]

There's a near new turbo for an intercooled 2.8 for sale on trademe at the moment.Performance parts P8.Hope this helps somebody,I don't need one but probably will after it's sold.

[geeves]

One thing that does affect diesels is the injector timing Ive always wondered how to check it and how often I suspect it is a job for the experts If its out one way the engine runs hot if its out the other the engine has a huge diesel knock and runs hot. A dyno should sort these probs out.

[Dave M]

Used to notice the oil pressure drop back a bit ( to arond 1.8 bar) when pulling the caravan up big hills, but the water temp never came up much. The underside of the pistons are squirted with oil to cool them. When under heavy load for long periods the oil gets hotter and the pressure drops a bit. The standard oil cooler (under the filter) barely does its job, especially if the fuel delivery has been increased or the boost wound up. Diesel experts have said to me these engines can retain heat and the best solution is a big bore exhaust. Shall be throwing one at my 2.8 soon as $ allow.

[Dave]

I will also be doing the exhaust on the Bighorn as soon as I can afford it (there goes the front lokka! ).
Cracked the head on all 4 cylinders, so $4000 later I have decided to play it safe, and I thought I was doing the right thing by getting rid of the Surf so I didnt have these problems again.

[PeterSchurms]

I found a turbo specialist (25yrs) in melbourne who overhauls Turbos at a bargin price and can also tunes desiels using a pyrometer and exhaust temp gauge. He tells me that the exhaust temp under load is a indicator of how in tune the engine is. This is providing the injectors and valves are within spec. His tuning rules for a 2.8 - 3.1 Lt desiel is 550-600deg under load measured 2inches below turbo exhaust. Higher than 800deg is a problem for turbos and engines. VDO make a gauge for $300. Too exspensive for me just at the moment.

He looked at my turbo and told me that is not working properly at all. He took all the numbers and looking into it. He is confident that it can be overhauled by looking at it (much to my supprise). This is to be confirmed though. If depends if it has steel roller bearings or another type.

I am dealing with three items now. Injector timing/pressure, valve tappet adjustment and turbo interal seal wear. I understand max fuel =max burn = max temp so if the valves are not adjusted correctly and not enough exhaust gas escapes, excessive hot exhaust gas could be left in the cylinder and increasing running temp. If the pump is pumping excessive fuel this can be a problem and if the exhaust is leaking/ loosing boost, the hot exhaust gas may feed back through the system increasing the heating issue.

I am taking mine in for the valves, possibly injectors and turbo overhaul on Tuesday. Hope to have it back Friday.

Wayne, I agree with your comments regarding acceptable temperatures and oil pressures, but I get nervous when power drops considerably with oil pressure. (I have been lucky that compression is still OK). This is the reason for following this up.

Geeves, I'll ask the turbo guy where to adjust the injector timing and post it. Maybe someone out there knows and can enlighten us. I understand there are consequences related to makeing these sort of changes.

[wayne]

That makes things a bit clearer Peter. If the power drops considerably with oil pressure I'd be worried too.
Setting the tappet clearences is an easy job for the average home mechanic.
Will be interesting to see what sort of pyrometer readings you get.

W.

[justin]

Pete, I'd be interested to see if you can get your Turbo serviced as I researched this for 3 months on both sides of the pond and the resounding answer was the units supplied to the 4JG2 motor were IHI RHF5 VIAO non servicable, (unlike the 2.8 units). If you by a new replacement unit for the 4JG2 IHI have updated them with a servicable model now, so as I have one in my garage that needs a service let me know if he does it and how much as that's a spare I could do with. J

[PeterSchurms]

Justin, I'll keep you posted on the service/turbo overhaul results.

[MattMU]

Sounds like you are on the ball, everything you have said in regards to Diesel tuning is spot on.

If a diesel isnt operating correctly (efficiently) then the temp will rise, as mine does too!

Timing and tuning a diesel is very specialised, there is a timing light you can hook up which uses the pulses in the injector line to fire the light. Timing is then advanced or retarded by rotating the injector pump, hence the little timing increments on the side of the pump timing cover.

Also the injectors are critical, if the delivery valves are not spot on the injector will inject early or late and not at the righ pressure and not for the right amount of time. Might also dribble and not have the right spray pattern, again throwing the tuning and mixtures (so to speak) out of whack.

It is all critical and not something you can play with in one area and expect gains, it all has to be competantly checked and adjusted as a system (that it is).

Personaly, if you havent had the injectors service by a pro, then I would be looking at that, then timing and then finally dyno tune, after that its turbo and exhaust temps! Its just a logical way to go...not going straight for the turbo first, in general.

Good luck with it all, we are all in the same boat and the more turbo diesels out there the more this area will be studied and perfected, as we all did with petrols years ago! Un fortunately there are a few servicing agents out there talking up alot more than they know, it is a very delicate area, not what we have seen in the past with diesel engine technology!

Matt.

[PeterSchurms]

Thanks Matt, Its good to know I am finally starting to make some sense with this problem.

Does anyone know what I could expect to pay to get the injectors serviced/replaced?