EGT probe location

[bods]

Yes, that is correct. Obviously the probe in the egr port will mainly read the temp from cylinder 4, but they should all be the same temp anyway. If you do decide to put the probe in the manifold pre turbo, you will have to remove the turbo beforw drilling and tapping the hole, to ensure no swarf gets into the turbine side....

 

[1310/71]

And if you do install the probe in the EGR port, you will probably end up completely removing the EGR pipe off the engine and just run blanking plates either side (with the exhaust side drilled and tapped for your probe). These plates should be reasonably thick if you do remove the pipe totally. Thin plates can flex with heat and leak. That doesn't necessarily occur when the pipe is still bolted on if just blanking them off.

 

[user 5942]

Thanks again guys, that's really helpful.

But I must ask why is there such a big difference between egr and pre-turbo temperatures if they are so close together?

 

[bods]

The egr port and pre turbo will be the same. The difference is in pre turbo and post turbo (in the dump pipe)

 

[user 5942]

The egr port and pre turbo will be the same. The difference is in pre turbo and post turbo (in the dump pipe)

Aye, right, probably mixed pre and post. Sorry if I ask so many question, by I'm learning a lot from this! A few more ..

- I assume pre-turbo tells you how hot the engine is running, i.e. if you're gonna "melt" it any time soon, but what is the benefit of knowing post-turbo temperatures?

- What makes the post-turbo run hotter?

- With the blanking plate on the EGR, how thick is thick enough? would 1.5mm do? Need more?

Thanks again!

 

[bods]

It's all good lol. The only stupid questions are ones that don't get asked and you end up wrecking something...

Pre turbo gives you, as you put it, an idea of when you are going to start melting things. I believe alloy starts melting at around 800c, the pistons are made of alloy, so you want to stay away from that hot.

No "benefit" in knowing post turbo temperatures. The main reason used to be in case the probe broke away, if fitted pre turbo it would be eaten by the turbine wheel, which isn't good. Technology has improved a lot since then and thermocouples now are generally sealed so they can't break apart under normal operating conditions. Post turbo is also a lot easier for fitment. Unless you remove the whole egr system, you have to remove the whole turbo to drill and tap the exhaust manifold, which isn't ideal.

Post turbo will show a lower temperature than pre turbo. Obviously the turbo uses heat energy and flow from the exhaust gas to power it. So in doing this it removes some heat from the actual cylinder temperatures. Under very high load there can be around a 200c temperature difference between pre turbo and post turbo (pre turbo being hotter).

You'd want a 4 - 5 mm plate on the exhaust manifold side of the egr if you are going to tap a thread to screw a fitting in. If you are going to weld a threaded bung into a piece of steel you could get away with around 2mm, but you would have to cut the ends off your egr pipe and use the thick end plates to reinforce the plate with the thermocouple in it.

Hope that helps a bit.

 

[bert546]

Cummins , Caterpillar and Detroit all have the probes after the turbo, usually 100-150mm . So thats good enough for me . I have never seen a truck or earthmoving machine engine with the probe in the manifold .

 

[PaulOsborne]

Your probably looking at the pipe from the EGR valve itself to the intake manifold. There's another pipe that goes from the back of the exhaust manifold (next to the turbo) around behind the engine to the EGR valve. We remove that pipe and put a plate on the end of the exhaust manifold and tap it for the EGT probe.

Rumpig, interested in this rear EGR pipe you've taken off and plated the exhaust manifold, is this part of the stupid emission control design?? My D40 stopped
one day blowing white smoke but was idling ok, i found out that the EGR valve
broke off and couldn't shut therefore there was no pressure in the intake manifold.
I had been reading a lot about guys putting a blocking plate to stop the crap going into their engines, so i made a plate put it in and presto drove home. I couldnt believe the crap deposited around the EGR/intake manifold when i took it apart.
Is this why you remove this other rear pipe??

Os

 

[Rumpig]

Rumpig, interested in this rear EGR pipe you've taken off and plated the exhaust manifold, is this part of the stupid emission control design?? My D40 stopped
one day blowing white smoke but was idling ok, i found out that the EGR valve
broke off and couldn't shut therefore there was no pressure in the intake manifold.
I had been reading a lot about guys putting a blocking plate to stop the crap going into their engines, so i made a plate put it in and presto drove home. I couldnt believe the crap deposited around the EGR/intake manifold when i took it apart.
Is this why you remove this other rear pipe??

Os

The D40 and ZD30 have different plumbing for the EGR system (which is part of the emissions system) but it works the same way. The pipe doesn't have to be removed, you just slip a plate in near the manifold end of the system, but once it's blocked it was easy enough to remove the pipe and put an EGT probe in the end of the exhaust manifold.