Just finished head gasket job. EGT question?

tcoilburner · **Posted:** Sun May 03, 2015 10:30 pm

I just finished doing a head gasket job, that ended up doing the a EGR delete and intercooler because it was leaking. I had a pyrometer installed just after the turbo prior to this. Now that I have had the manifold off, I moved it to the opening just be the turbo. The temps there I realize will be hotter most of the time, but it seem like it might be too hot. I am worried that when timing the motor that I got it a tooth off. I had to remove the crank holding pin and turn it slightly to get the belt on. The temps it has been running this week are as follows. Easy run in to work allowing it to coast about a 1000 yards from the road to a parking space temps are still at least 450. On cold start up, walk away from it and 3-4 mins later come back and it is reading 300-325 degrees. At a steady run mostly flat in 4th gear at 57mph it was running 700-800 degrees. I got the camper out friday night and towed it home temps running 1100-1200 degrees with 1300 hitting on a couple of small hills. Is there a way to check timing using a Chrysler Starscan scanner using the cam and crank sensors? Any thoughts would be very welcome.

Mountainman · **Posted:** Sun May 03, 2015 11:45 pm

I don't know about the specific temps, but I'd go run it WOT a few times on a flat road watching the temps to make sure they're not getting too hot. That will help if the CAT is plugged, which will cause high temps, especially if you drive with really slow acceleration most of the time.

It would be gutless, quite noticeable if you are a tooth off. You can put the crank mark at the 3 o'clock, and try to pin the cams, and if it doesn't go, move it around one rotation back to 3 again, and try to pin the cams. If they line up good, then you got it right. Forget about the pinning the crank :2cents:

Auberon · **Posted:** Mon May 04, 2015 2:14 am

With regard to operating temps:
These temp conversions are give or take 3 degrees or so - it isn't that critical.
Can't get that precise when you're driving.
NOTE: My EGT sensor is right in the centre of the INLET to the TC so from your description is in same spot (or there abouts).
So it would seem we can compare like with like. It responds incredibly quickly to any load change or odd occurrence.
You've done a good thing here. Tells you bucketloads about things potentially going awry far quicker than water temp or any other thing or running normally.

Re temps:
I only switch off after it has idled for a minute or so at 250 C (480 F) - dependent on how hot she got during the run.

At cold idle it sits consistently at the 250 C level....it's actually a tiny bit cooler than this but that is the lower limit of my gauge.
It's really surprising - I've read about lots of blokes who say it's an easy run or roll into the car park and that should be good enough. It is absolutely not.

Got to say my EGT's take much longer than a gentle roll in a car park (unless its at absolute idle to lose that reserve of heat). Any throttle at all keeps them up a bit even then it has to be a dang long way to take them to 250 C (480 F).

Rolling along a very flat road (to describe how flat: it runs beside our local RAF base for the whole length of the runway and then some) gauge sits steadily at about 285 C (545 F) at a speed of 50mph (speed limit and patrolled by police). Engine load is only around 25% (calculated).

Climbing hills it can get up a bit but I've set an upper limit to EGT of 750C (never got there yet) which corresponds to 1380 F.
With a trailer laden to about 1700 kg up some very steep hill near home the hottest I've achieved on a 120 F very humid (100% RH) summer day was 625 C (1160 F) but that number is from way-back.

Expect some flak over your method with the timing belt. It can't be helped by some. The method seems to have worked for you but as mountainman suggested it is worth an extra check - mainly for your peace of mind. This belt is pretty darned hard to get on especially if you don't pull the whole front end off and you don't do it often. You find muscles that are long forgotten. I reckon a physically able person would find it hard enough to reach it all (I did mine with the stack in place and I'm gimped rather badly). Leaving the heat exchanger stack in place makes it a bit of a physical stretching job but it is certainly doable. Agree with mountainman about the car being "gutless" if you were off a tooth.

Now your back up and assembled you can at least load your motor at controlled hard runs limiting EGT to just under your chosen upper limits - so can work it without driving as though you stole it as you have a safe-guard against killing it. Also agree with him about the quick re-time to check.

In fact, you can work it longer and harder with less likelihood of damage as you'll get a reading to tell you to ease off. Towing your trailer may well be your friend in this case as you'll be able to load it constantly at peak temp and change gears appropriately to let it breathe better and control temps.

Hope that helps

tcoilburner · **Posted:** Mon May 04, 2015 7:17 am

Auberon your temps seem to be right inline with mine. I have been reading other posts and I thought mine was very high. I will try to check timing this week. Thanks both of you.

thermorex · **Posted:** Mon May 04, 2015 11:24 am

Auberon, it takes me between 30 secs to 2 minute, depending on highway driving stop or city driving stop, to reach 300F degrees when idling. All engine load switchable consumers are off. Highest I tested was mid 90s with close to 100% humidity. I have the probe on cyl 3 exhaust.

geordi · **Posted:** Mon May 04, 2015 2:38 pm

pre-turbo temps (I had mine mounted in the mouth of the turbo too) will be about 300-350 higher than post-turbo. Post turbo temps are where you don't want to EVER be seeing 1300+

The CRD (according to Keith) can drive all day long with 1100-1200 pre-turbo temps, as that means the outlet temp is only around 900. You should give it a bit to cool before shutting down, but temps of 480 pre-turbo translate to 180-200 post-turbo. Warm, but not bad at all.

tcoilburner · **Posted:** Mon May 04, 2015 3:20 pm

I don't think mine would get down to 300f after the engine warms up. At idle cold engine it now is at 300-325f after a few minutes. Also after the engine is hot, if I allow it to cool down to 375, and just put it in gear no a/c, it heats back to 400-425 sitting still.

thermorex · **Posted:** Mon May 04, 2015 6:08 pm

tcoilburner wrote:

I don't think mine would get down to 300f after the engine warms up. At idle cold engine it now is at 300-325f after a few minutes. Also after the engine is hot, if I allow it to cool down to 375, and just put it in gear no a/c, it heats back to 400-425 sitting still.

Correct, my Egt never drops under 400 with jeep in drive.

Auberon · **Posted:** Tue May 05, 2015 1:33 pm

It's important that gauge responses are not delayed by anything other than the thermal inertia of the SS probe which is about 15 sec. This way you are only measuring the temp of flowing gases and not the "latent" heat or residual heat of a body of Cast Iron.

The fact that I'm measuring in deg C is a problem - the scale is quite a bit more compressed than the Farenheit scale although I grew up with the imperial scale and we changed to metric ----rude words - doubled the tools in the workshop.

This location is so indicative that a 10% increase in calculated engine load brought about by a slight hill or some acceleration almost always results in a 10% increase in EGT until it stabilises and then drops a little again. You'll like it tcoilburner.

I know that my engine run temp is within chosen limits and I allow a bit of extra time to let the heat run out of the turbo heat sink.
After being at 280 C it comes back to 250 C (gauge lowest reading) after a period of 15 sec. Any higher/hotter running and the whole engine takes significantly longer to cool down and start allowing cooler gases through.

That would be about the longest delay I note for readings to change but that is the thermal inertia of the SS sensor.
At home I've done a good run and then taken temps with a laser pointer to confirm carry-over time for dispersing heat away from the Turbo body as it cools....this is why I'm surprised some are so ready to switch off so soon.

The EGT drops much more slowly than folk realise in the body of the turbo as does the clearing of any carbon that can deposit itself on vital engine components. There is a certain amount of radiant heat from the body of the turbo despite the overall exhaust gas vector pulling it out of the engine. It should only be a passive component at idle and not acting as a compressor.

The importance of an appropriate idle down period cannot be overstated and I am troubled by those drivers who follow the table provided in the owners handbook.
I intentionally leave the accessories switched on to slow (extend) the "warm-down" - clears the cobwebs out and lets any residual carbon go out with the exhaust gasses (especially with the GDE tune). Exhaust gases are so clean they smell like a very clean unleaded gasser engine.

I don't idle her down in gear but leave the A/C on.

1300 F is the absolute upper limit I would let it go to ever and given the way it runs - well gee you'd have to be pushing darned hard to get it there and keep it there. I'd confirm that EGT Geordi noted as a sound basis for continuous running.

Just as an aside I finally set aside the time to sort out the In /Out temp gauge for the CAC cooler. Haven't been for a drive yet - but that's certainly better than reading the temps on my A/C condenser - where the thermistors sat until sorted

.
That will be interesting and I think very telling about the health of my CAC system.

I rarely run stop-go or true highway most of mine is done at 50 mph due to the local speed limit. Fairly constant style of running really with little traffic and that spongy original Torque converter. It will ease the pressure on the whole rig up ever so much when the replacement goes in. Just have to fabricate the scissor lift for it now.

[quote="tcoilburner"]I don't think mine would get down to 300f after the engine warms up. At idle cold engine it now is at 300-325f after a few minutes. Also after the engine is hot, if I allow it to cool down to 375, and just put it in gear no a/c, it heats back to 400-425 sitting still.[/quote]

That seems about normal behaviour and your already gaining the sensitivity of siting the thermocouple as you did.

tcoilburner · **Posted:** Wed May 06, 2015 6:02 pm

I have not had time to check timing yet. Maybe tonight.
Just ran a full throttle run from 30-70 mph. The temperature run up to 1500f when I got to 70 and let off.
Some thing doesn't seem right. Keith said it can run 1300 no problem, short intermittent to 1400.

Auberon · **Posted:** Fri May 08, 2015 12:48 am

A WOT hard acceleration will rapidly punch gas temps up to that level due to the location of your sensor.
Then it will stabilise.
I realise this is probably stating the obvious to an intelligent bloke but:
A steady run will spread the heat through the system then it'll drop back as the heat soaks through the system. If it's radiating from evenly from all radiant surfaces and THEN stays elevated it's time to worry.

If, after heat has soaked and longer hard running do you get a stabilised elevated EGT?
either:
under load (which could be WOT) - that tells you its time to back off or if you're towing a load - drop a gear. Let her breathe.
Comment: Thing is you can't sustain WOT so it's an artificially loaded situation and WOT does not have to be flat to the boards.
OR
If I'm not reading your words rightly, please tell me.
You did that under WOT acceleration only and did not do a stable hold.....Yes?:
I'm curious to know what it reads when you go at it normally and accelerate to 70 mph in your usual manner and hold that speed.
If it holds the elevated temps after normal acceleration and just running along at 70 mph - then you may have a problem.
If you did a hold for a substantive period, what does it do?
I suspect you'd probably peak and then drop back if you held 70 mph....but of course, I'm not driving it.

I realise this is an ask but:
The type of gauge that tells you Calculated Engine load UltraGauge, Giotto (AE) etc tells you reams when doing this kind of figuring....also TPS duty cycle etc. Any chance you have one in your KJ?
Do you have any idea what your Calculated Engine Load might have been - from a gauge reading the ECU?
A guess is futile.
Cheers.

geordi · **Posted:** Fri May 08, 2015 1:08 am

tcoilburner wrote:

I have not had time to check timing yet. Maybe tonight.
Just ran a full throttle run from 30-70 mph. The temperature run up to 1500f when I got to 70 and let off.
Some thing doesn't seem right. Keith said it can run 1300 no problem, short intermittent to 1400.

The temperatures that Keith is usually quoting are AFTER the turbo, so take your temps and subtract 300 degrees to get the approximate turbo-outlet-temp that would fit in Keith's data.

Also, Auberon is not wrong with his post. Heat soak is worse than a fast 'Italian tune-up' WOT run. Unless you are trying to tow a building, you shouldn't ever see 1500 sustained pre-turbo with a mostly-stock setup. I don't think you have anything to worry about.

Auberon · **Posted:** Fri May 08, 2015 1:34 am

Geordi, just to let you know I just added a few words as a qualifier to the bit about holding at 70mph. No big differemce but it isn't implied anymore. S'all.

CATCRD · **Posted:** Fri May 08, 2015 9:29 pm

tcoilburner wrote:

I just finished doing a head gasket job, that ended up doing the a EGR delete and intercooler because it was leaking. I had a pyrometer installed just after the turbo prior to this. Now that I have had the manifold off, I moved it to the opening just be the turbo. The temps there I realize will be hotter most of the time, but it seem like it might be too hot. I am worried that when timing the motor that I got it a tooth off. I had to remove the crank holding pin and turn it slightly to get the belt on. The temps it has been running this week are as follows. Easy run in to work allowing it to coast about a 1000 yards from the road to a parking space temps are still at least 450. On cold start up, walk away from it and 3-4 mins later come back and it is reading 300-325 degrees. At a steady run mostly flat in 4th gear at 57mph it was running 700-800 degrees. I got the camper out friday night and towed it home temps running 1100-1200 degrees with 1300 hitting on a couple of small hills. Is there a way to check timing using a Chrysler Starscan scanner using the cam and crank sensors? Any thoughts would be very welcome.

Your numbers seem high to me. I have a GDE hot tune and pre turbo pyrometer. With a fully warm engine, EGTs will stay at about 200F above ambient idling in park. Hold the vehicle still in gear and it will idle at 300F over ambient. 75mph cruise on level ground is 500 over ambient, with 13-15psi boost. These numbers are without AC or other accessories.

tcoilburner · **Posted:** Fri May 08, 2015 11:09 pm

I believe that they are high too. I think back now and believe I tightened down the cam gears before the belt was on ,not after. Causing me to need to undue the crank pin. I am betting that it's off 5to 10 degrees of timing. I will be getting back down to the belt Sunday or Monday. I am finding that as the weather is warming this week it is taking even longer to cool down after a run. Even light acceleration when the torque converter locks in third gear temp go right to 950-1000f. The mileage is off 2-3 mpg from before on long runs.
CATCRD, I am thinking of going to the hot tune to make pulling our camper easier. Do you tow? What kind of temps do you see on grades if you do? Thanks everyone.

CATCRD · **Posted:** Fri May 08, 2015 11:30 pm

I tow a really small popup sometimes. Not really worth mentioning.

tcoilburner · **Posted:** Sat May 16, 2015 1:35 pm

Finally checked timing and had time to post.
The timing was one tooth advanced (I believe) on the crank. Now it is correct and has towed the camper again, and temps stayed below 1200f pulling a hill. Definitely seemed to pull it a bit better.
The only thing that is not quite right is the mileage. I am still about 2 mpg short of what I was getting most of the time. Not towing that is. I am getting between 24.5 to 25.7 at 55 to 57 mph. No, codes and no lights on.

Just finished head gasket job. EGT question?

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