EGT and boost number question

thermorex · **Posted:** Fri Jun 20, 2014 8:21 am

Hey Guys, quick question(s) for you. I just installed an EGT and boost gauge (both glow shift).

First question: The EGT probe is installed in the exhaust manifold on Cyl #3. I have noticed that after a few minutes drive, stop and idle for a while, the temp never gets lower than 300-ish degrees. Idling for 5 minutes after a normal highway drive, at about 60mph, the EGT dropped to about 280 degrees. Is this normal for CRD? I know that running the OM617 from the Mercedes 300SD for not more than 3 minutes, will make the temp drop to about 200 degrees (probe is also installed in the manifold, on cyl #4). I just wonder if the extra set of 2 valves/cylinder can make the temps on the CRD be a bit higher.

Second question: The boost gauge I installed does not have an electronic sender, it has a vacuum hose that connects to the gauge. It also has a vacuum, so it reads vacuum as well as boost (link to the gauge: http://www.glowshiftdirect.com/black-7- ... gauge.aspx). The vacuum line feeds from the intake cover, right above the elbow. When idling the needle twitches between 1 vacuum and 1 boost very quickly (needle shake). The gasoline engines (especially high performance race vehicles) with a vacuum gauge have the tendency to do this if the intake and exhaust valves overlap (normal for those engines). While driving, the needle stabilizes and it barely twitches, you can only see the movement if you really pay attention to the gauge, the movement is almost unnoticeable. I wonder if this is normal and if you guys have experienced a similar behavior. Also, worth to mention, the gauge comes with a plastic soft hose, which I did not use, I use instead the standard vacuum lines from hard plastic with rubber hose connections at the end (rubber hose on the intake hose barb adapter and on the gauge). I also wonder if that supplied hose, being softer, can reduce the "needle shake" due to allowing some expansion.

So, to summarize: is it normal for the CRD to have 280-300 degrees EGT after idling for few minutes? And is it normal to have the "needle twitch" with a non-electronic boost gauge?

Thanks a lot!

CATCRD · **Posted:** Fri Jun 20, 2014 10:39 pm

If the AC has been running the EGT will take several minutes to drop below 300. If not it's only a minute.

diesel_guy86 · **Posted:** Fri Jun 20, 2014 11:30 pm

Mine hovers around 300 also, so must be normal. What temp do you see when cruising? also how much boost?

thermorex · **Posted:** Sat Jun 21, 2014 12:11 am

Thanks guys! I wasn't running with ac on, and I left it about 5 min on the clock to idle, it fell at about 250-ish. Anyways, under 300 should be safe imo, the oil doesn't get cooked at that temp. I also didn't floor it, I get regulary 15 psi boost in normal hwy drive, when I go slightly uphill on the highway on 5th. City drive is in between 5 and 10 most time. I'll hammer it these days to see what the max boost will be, I'll look for a hilly road.

65Corvair · **Posted:** Sun Jun 22, 2014 2:20 pm

Most I have seen is 21psi and 1100F. Mine also idles around 250F if I let it sit long enough. 300F is usually when I shut it off. Any type off additional engine loading will increase EGTs.I have this gauge so I can't comment on the needle twitch.
http://www.glowshiftdirect.com/3in1-EGT-Boost-and-Pressure.aspx

WWDiesel · **Posted:** Sun Jun 22, 2014 8:00 pm

65Corvair wrote:

Most I have seen is 21psi and 1100F. Mine also idles around 250F if I let it sit long enough. 300F is usually when I shut it off. Any type off additional engine loading will increase EGTs.I have this gauge so I can't comment on the needle twitch.
http://www.glowshiftdirect.com/3in1-EGT-Boost-and-Pressure.aspx

I clicked on your link, I found no listings for Jeep CRD.
Where is the Jeep items listed? :?:

diesel_guy86 · **Posted:** Sun Jun 22, 2014 9:10 pm

Its a universal gauge.
On another note, what egts are you guys seeing at cruising speed? With my altered crd I'm seeing 900-1,000° egt and 5-7psi boost while cruising.

thermorex · **Posted:** Mon Jun 23, 2014 8:34 am

I have that exact universal 3-in-1 gauge installed on the Mercedes OM617, but haven't seen any twitch on the boost, other than because it's obviously a digital display, lol, but I think any digital boost sender won't show that "twitch". I was just curious if anybody saw that on a mechanical gauge. I'll make a short youtube video and post it sometime today.

In regards to EGT, my temps are 6-800 on highway cruise, depending if it is slight uphill, straight or slight downhill. City drive is about 4-500 going constant at 35-40, but as soon as I accelerate even a tiny bit, I get 1-200 degrees more. I did step on it on Saturday going up the ramp towards the highway, the boost made a quick jump to 22, then fell at about 17, then gradually at 15 till I loosed the acceleration. I noticed that boost is anywhere between 5 and 10 on highway cruise. EGT got close to about 900, but not more than that, I also didn't tow uphill, nor I accelerated for sustained periods, this is with jeep going straight and no trailer. I am pretty sure it will be around 1000 with some load and going uphill for some time.

diesel_guy86 · **Posted:** Mon Jun 23, 2014 9:00 am

Based on your numbers then I'm pretty close to stock, slightly warmer and little bit less boost. I think the new turbo I'm getting should get me back to stock numbers. Thanks!

thermorex · **Posted:** Mon Jun 23, 2014 9:23 am

Yea, I think if you have a bit more boost, then the egt temps should decrease a bit.

thermorex · **Posted:** Mon Jun 23, 2014 8:38 pm

This is a short video while idling, the twitch seems way worse in the video due to probably refresh rate and camera quality, the needle is never going above or below the thick 0 mark. Plus, the lights don't flicker at all.

Crd boost gauge twitch: http://youtu.be/v3ER1jZ70Xs - > removed.

New - > Crd mechanical boost twitch: http://youtu.be/MxHE33obpOg

flash7210 · **Posted:** Mon Jun 23, 2014 9:24 pm

Wow, that video looks weird.

So the twitch only occurs at idle?
I'd say that's pretty normal for a mechanical gauge.

WWDiesel · **Posted:** Mon Jun 23, 2014 9:36 pm

They do make a thing called a snubber in the gauge world that smooths out the pulsations on mechanical gauges. I have one on my Dodge Cummins fuel pressure gauge tapped in on the outlet side of the fuel filter. With out it (mechanical gauge), it would self destruct in short order due to the constant pulsations (bouncing) at idle! :wink:

thermorex · **Posted:** Mon Jun 23, 2014 9:51 pm

The twitch is more noticeable while idling, but it does some lighter twitch while driving also, I'd say probably 10-20%.

I'll see if I use a better camera, maybe I get e better quality of the gauge needle twitch.

I'll look for a snubber, thanks a lot!

Edit: I wonder why the gauge won't come with a snubber...

thermorex · **Posted:** Tue Jun 24, 2014 6:31 am

I edited the previous post with the new link to video: Crd mechanical boost twitch: http://youtu.be/MxHE33obpOg

WWDiesel · **Posted:** Tue Jun 24, 2014 7:02 am

Look on eBay, they have many snubbers listed.
This site also has a good selection:
http://www.dfs-gauges.com/category/pressure-gauge-accessories/pressure-snubbers.aspx

A snubber will solve your problem! :JEEPIN:

thermorex · **Posted:** Tue Jun 24, 2014 8:54 am

WWDiesel wrote:

Look on eBay, they have many snubbers listed.
This site also has a good selection:
http://www.dfs-gauges.com/category/pressure-gauge-accessories/pressure-snubbers.aspx

A snubber will solve your problem! :JEEPIN:

Thanks, I already ordered one

.

WolverineFW · **Posted:** Tue Jun 24, 2014 9:12 pm

thermorex wrote:

Edit: I wonder why the gauge won't come with a snubber...

Answer: Money

diesel_guy86 · **Posted:** Tue Jun 24, 2014 9:30 pm

How's your rockers?

thermorex · **Posted:** Wed Jun 25, 2014 6:54 am

I had them replaced last year, and the MAF readings are also good. The gasoline high performance engines have this issue with vacuum due to valve overlap, I need to take a look on how camshafts are at crd, I have a spare valve cover with cams. Or, my timing is a bit off, but not enough to create problems, which I find hard to believe but I guess can be possible.

I'll try the snubber when I get it and see if it makes a difference.

Joe, do you have a digital boost gauge or a mechanical? I know that a digital won't have this issues, I wonder if somebody with a mechanical gauge (which has an air hose in the gauge, not only wires) with no snubber has the same behavior.

EGT and boost number question

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