Exhaust Gas Temps

[freeheelsteve]

Hi Everyone,

I have read through a bunch of posts on this and have a general idea on temps from the pyrometer.

I just had a new turbo installed and I had my mechanic install a pyrometer before the turbo. He and I are both concerned we are seeing temps too high to be safe during highway driving. I need to test it a bit more but I'm wondering what people are seeing while driving 100kph on flat highway and does the temp jump around quite a bit. Seems like during acceleration, the temp really jumps up (to like 1300F).

If I am having abnormally high temps, he and I were discussing probable causes. He mentioned injectors, but told him I had CVI take care of that last year with a Delica Tune. Also, I don't get any black smoke. Any other suggestions.

So, I guess my questions are:

1. What exhaust gas temps are people seeing at 100kph with pyro mounted pre-turbo?
2. Other probable causes of high exhaust temps

Thanks and I'll report back after I drive it a bit more today. By the way, it's a 5 speed, 1994 (water-cooled turbo)

Cheers,
Steve

[jessef]

Hi Steve

94 5-speed what ? L300 or L400 ?

1300F pre-turbo is high if just cruising.

What is it reading when you floor it going up a steady hill under load ?

That's the best test.

On flat highway, I've had mine hit 1,200+ F pre-turbo but I was going 110km/hr against a good wind on my L300.

While keeping it between 90-100 and then accelerating, I can easily run it past 1,250F on flat highway if I push it.

Average highway reading for my 5-spd was 800-1,200 highway depending on cruising speed/acceleration/grade.

The L300 is shaped like a brick which is not the most aerodynamic and it weighs a lot. The little 2.5 runs hot when the pedal hits the floor and when cruising above 90km/hr.

What tires (diameter) are you running ?

[freeheelsteve]

Hey Jesse, thanks for the quick reply. I drove to Kelowna and back to Vernon today and discovered that a previous problem which we thought was related to exhaust manifold leak and cracked turbo housing is not in fact fixed by repairing those two things. In fact it may be this problem that is giving me such high exhaust gas temperatures and in turn cracking manifold and turbo housing. I was ready to drive the thing off a cliff today.

The original and still pending problems are gradual loss of power during a longer drive. So, starts out with good boost and no problem doing 100kph and climbing hills but after 50km or so I will notice loss of power around 2500rpms in 1st gear, so then I just change and keep going. This keeps getting worse untill it won't accelerate above 2500rpms in any gear and I'm stuck limping the thing home at 75-80kph in 5th gear. Going downhill in 5th gear and trying to do 100kph feels like the brakes are on. It's ridiculous.

My mechanic and I are both hoping it is not the cylinder head. Anyways, looks like I'm getting a compression test done next.

Any insights? It's a 94 5speed L300 by the way.

Cheers,
Steve

[jessef]

Was the injection pump rebuilt ?

Usually fuel/air delivery but in your case it's good and gets worse over time.

Something's slowly giving. Good call on the comp test.

Post your readings once you've got them.

[loki]

Hey Jesse, thanks for the quick reply. I drove to Kelowna and back to Vernon today and discovered that a previous problem which we thought was related to exhaust manifold leak and cracked turbo housing is not in fact fixed by repairing those two things. In fact it may be this problem that is giving me such high exhaust gas temperatures and in turn cracking manifold and turbo housing. I was ready to drive the thing off a cliff today.

The original and still pending problems are gradual loss of power during a longer drive. So, starts out with good boost and no problem doing 100kph and climbing hills but after 50km or so I will notice loss of power around 2500rpms in 1st gear, so then I just change and keep going. This keeps getting worse untill it won't accelerate above 2500rpms in any gear and I'm stuck limping the thing home at 75-80kph in 5th gear. Going downhill in 5th gear and trying to do 100kph feels like the brakes are on. It's ridiculous.

My mechanic and I are both hoping it is not the cylinder head. Anyways, looks like I'm getting a compression test done next.

Any insights? It's a 94 5speed L300 by the way.

Cheers,
Steve

just a thought, try pulling over and taking off the fuel filler cap and putting it back on after it has started to lose power, could be the tank isn't venting and is causing a vapor lock? the other thing to check is the fuel return, try taking the return line off and putting a new short hose on that runs into a container of some kind see if it runs better after that.

could well be that you have already thought of those things though :)

[FalcoColumbarius]

Regarding temperature, have you checked the radiator cap for cracks? As far as a cracked head theory goes I'd check the oil cap for water and check the coolant for oil. How often do you change the oil?

Falco.

[dennis_lambert]

Just another thought,If your boost is set way to low it might cause a increase in Egt.Also maybe have a look over your exhaust system.a severe restriction could possibly cause some of the symptoms you are describing.maybe the pipe was hit by a rock and bottlenecked..
When is the last time you had the fuel filter replaced?
My Egt thermocouple is mounted after the turbo on my 94 which is a water cooled turbo and heading up to big white ski hill I can hit 1200F easy..my boost setting are stock.I am going to increase boost as soon as i install a boost gauge and will post the difference in EGT.
Do you live in vernon?
cheers
Dennis.

[FalcoColumbarius]

Just a side note regarding boost levels: Between eight & nine PSI is the optimum sweet spot, according to an ex-military turbo mechanic guy I know. Apparently if you increase the boost from that point the turbo spins faster but collects less air. That's what I heard, anyway.

Falco.

[dennis_lambert]

Just a side note regarding boost levels: Between eight & nine PSI is the optimum sweet spot, according to an ex-military turbo mechanic guy I know. Apparently if you increase the boost from that point the turbo spins faster but collects less air. That's what I heard, anyway.

Falco.

Yeah i think your right if you crank your waste gate closed too much the turbine will spin the compessor so fast the air will have no where to go and possibly cause a compressor stall.I am not too sure but dont these Delicas have blow off valves to prevent that from happening though ?

[freeheelsteve]

Hey Guys,

Thanks for all the tips. I'll keep them in mind as I go forward.

Dennis, I do live in Vernon and unfortunately I could get the EGTs to hit 1300F just going up a slight incline on the highway the other day. I just had my pyro installed since having problems, but now I'm worried I've been running really high EGTs for a while now without even knowing it.

Wish me luck.

Steve

[Meanman]

loss of power once hot with excessive temps....check valve clearances. These two symptoms are a good clue to valve clearance being too tight.

[Erebus]

I get temps about the same as Jesse's, but I've got an automatic, and my pyro is installed post-turbo.

[Super Low]

I am reaching temps of 900C going up hill at 100km/hr (egt is pre turbo) boosting at 1.6kg/cm2 otherwise its 650-700 at 100km/hr. This is in a 95 L300 automatic

[fexlboi]

I am reaching temps of 900C going up hill at 100km/hr (egt is pre turbo) boosting at 1.6kg/cm2 otherwise its 650-700 at 100km/hr. This is in a 95 L300 automatic

Are you sure it's 900° Celsius? I'm surprised your heads are not already cracked.

[dennis_lambert]

900 Celsius is like 1600 F,seems way too hot..
Maybe there is a Difference where the thermocouple is mounted.Pre Turbo mounted probes appears to be a few hundered deg hotter then post mounted probes.
Do you guys with seemingly really hot engines ever see an indication of overheat on the coolant Temp?