Help needed, EGR EGT and Boost Gauge

[motoD22]

Hey all. First i know there are many threads on these mods but ive run into a bit of a problem and cant find an answer for the life of me. I decided to give the EGR mod and installing a boost and pryo gauge a go on the weekend. The forum has been incredibly helpful. Ive got the cabin all wired and the boost gauge plumbed in. EGR is done.

Problem came trying to locate a spot for the thermocouple of the EGT. Was going to put it in a plate where the egr pipe goes into the exhaust (Blue in Pic) as baitfish did in this post http://www.navara.asia/showthread.php?t=11612. However trying to undo the bolts at the other end of the egr pipe i managed to snap the bolt mid thread (Red in the pictures). From what i can see from the torchlight and feel, the cast bit the pipe bolts to only has the 2 egr pipes and the thing the wire harness n two large vac hoses go into (Yellow in pic) and doesnt connect to the block. Is this correct and what is this thing? I traced the top hose n it seems to go into one of the large hoses that goes into the cabin (Purple in pic). Would it be needed seeing as the egr pipes are going to be blocked anyway? I was thinking maybe looping the pipes together but as im unsure as to what it is and cant find it in the service manual need to find out first.

Next question, I took her out for a quick spin just to see if boost gauge was working n no hiccups with the egr. Went fine for a few minutes, 15psi of boost max which is good(?). Then a odd screeching sound started intermitantly. After a couple minutes I worked out it was when the turbo reached about 12psi it started. Anyone experienced this before? I have a couple ideas on where to start when I try again tomorrow. The obvious to me is the egr pipe with one bolt missing. Or possibly my gasket on my egr plate isnt sealed properly (Green in Pic). Or the black solenoid that is supposed to have the vac pipe looped on itself after the mods done; I accidently broke one of the inlets off so i left the pipe off as the thread said it was only for cosmetics (is this correct?). Could any of these make a screeching noise?

Thanks in advance for any help anyone can provide. It will be much appreciated

 

[Old.Tony]

I can't help with the EGR pipe issue. You could try using an Ezy-Out to remove the remainder of the bolt, but if the thing isn't needed then there's little point. However, the next issue might change things ...

The screeching sound could really only be two things.

The first, and least expensive to repair, is a boost leak. It'll sound like someone letting the air out of a balloon or blowing a high-pitched raspberry. This is probably related to the missing bolt but it could also be from one of the hoses between the turbo and the intake manifold OR it could be from an intercooler that's developed a hole or split a seam.

The other possibility is your turbocharger has let go - the screeching will be very high-pitched, like fingernails on a blackboard. It will probably be expensive to fix, but make sure first. When the engine is cold, clean the hose and the front of the turbocharger, clean your hands then remove the hose from the turbo's intake. Spin the compressor wheel then wiggle it from side to side. It should spin smoothly (although it might feel a little heavy to move because the oil is cold) with no grittiness to the turning, and it should not wiggle from side to side at all. If there's a gritty feel or any wobble in the shaft then the turbocharger is letting go.

 

[motoD22]

Cheers Tony. It was hard to describe what it sounded like before, but letting air out balloon is probably pretty close actually. So I'll start with the missing bolt, work from there

 

[joffo81]

Goodluck motod22 - hopefully its an easy fix boost leak for you!

Tony, I have a similar high pitch sound that I havn't diagnosed yet and am really hoping its not the turbo. The sound only starts or is only noticable from about 3000RPM. Does this occurrance sound familiar to anyone? Does a failing turbo make a squealing sound throughout the revs or only at certain revs?

Joffo

 

[Old.Tony]

A squeal at a particular RPM is more likely a boost leak, where the pressure is just right to cause the leak to vibrate and produce the sound. Below that pressure there's probably no leak at all, and above it it's an open leak (if anything, it'll sound like a gay man farting).

If there's a screeching sound that follows the RPM all the way up it's possibly the turbocharger. Give the thing a look-at and see.

Boost leaks are dead easy to fix and you'll recover a little power and economy by fixing them. Turbo failures are dreadfully expensive - over $1000 for the turbo alone, and if your engine is toasted by the debris, expect ten times that for the repair bill.

 

[dan-0]

Hey mate, I have done a couple of navaras and patrol EGR's.

Where is the boost screaching coming from? Cabin or under bonnet?
If its cabin, its just air escaping the boost gauge. Try tightening up the connection behind the gauge. If its under bonnet, I think it would be air escaping the EGR where your stud broke as it can no longer keep a tight seal at higher boost levels.

Remedy: good luck. Those exhaust studs are VERY hard steel. I broke a ZD30 turbo stud and I went through a set of 2 easy outs, 4 drill bits and barely shaved 3mm off it. I ended up just replacing the turbo. Where your stud is located you might not have that option. There is not much room down there.

I do all my EGR installs on the exhaust pipe, about 10cm from the turbo. This gives the most accurate results. All you need to do is take the exhaust off, drill a 5-10mm hole for the probe to fit through then weld a nut over the hole to screw the prove into. My local exhaust shop welded the nut on for free.

 

[dan-0]

A possible remedy for you is to blok the EGR off at the turbo manifold. This will stop the air even reaching the EGR with the broken stud.

 

[joffo81]

Thanks Tony. This sound has been present since I bought the vehicle 12mths ago and I don't really think it has changed. I have visually checked the front of the turbo before but I am inexperienced with them. Should there be absolutely no wobble in the shaft or is little OK? Is left to right wobble different to up and down wobble?
I'll have another look at the turbo and will also check the clamps on the 2 short hoses from the turbo to inlet manifold and the small hoses plumbed in for my boost gauge. Anything else obvious for me to check that I may have missed?
Joffo

 

[Old.Tony]

The bearings are circular so there should be no difference in left-right or up-down unless there's a broken bearing on that side of the shaft.

Because of the high revolutions made, these things need to be fairly precise. A small amount of wobble at 100,000rpm can be quite destructive. The bearings should be holding the shaft solidly in position with NO wobble.

Check the EGR tube. I you've blocked off the EGR, the side toward the intake manifold is under boost pressure (the other side under exhaust pressure). If there's a leak on the intake side, it may be evident as a squeal.

 

[rockcod]

The bearings are circular so there should be no difference in left-right or up-down unless there's a broken bearing on that side of the shaft.

Because of the high revolutions made, these things need to be fairly precise. A small amount of wobble at 100,000rpm can be quite destructive. The bearings should be holding the shaft solidly in position with NO wobble.

Check the EGR tube. I you've blocked off the EGR, the side toward the intake manifold is under boost pressure (the other side under exhaust pressure). If there's a leak on the intake side, it may be evident as a squeal.

I am under the impression that a turbo shaft will have a little play in it when cold and under no oil pressure, which is the most likely time you will be putting your fingers in there.

If there was no play at all how would it go when it was operating at extremely hot temperatures with expansion etc?

If the noise was to be the turbo wheel hitting the inside of the housing it would be quite obvious to see, so should be able to rule that out pretty easy.

Cheers,

Dave

 

[Old.Tony]

That's very true, something I'd forgotten. The exhaust side of the shaft can be subjected to over 700C - there'd be significant thermal expansion from that.

I might open mine up in the morning and have a look at it. No point trying it now, it'd still be warm.

 

[joffo81]

Thanks for your input fellas. I checked my intake hoses and tightened clamps. Then pulled front end off turbo. There is slight movement (1-2mm overall) up and down in the shaft but no sideways or end play. It really feels quite firm and looks clean inside thanks to the provent catch can. Movement in the blades is smooth. I am assuming due to the cold oil inside that the blades should not spin freely like spinning the handle on a fishing reel? It is the only turbo I have ever owned or felt so to me it feels quite good but I don't have a comparison. I would be interested to see if yours has any movement if you check it sometime Tony.
I took the Nav for a spin after it warmed up and it was still making the squealing noise. It gernerally does it at about 3000rpm as boost hits about 14psi and disappears at about 3200 rpm but I can make it make the sound anywhere from 2750-3500rpm with boost of 11-15psi depending on how it is driven.

Tony, could you please try to explain the location of the EGR pipe that I could check. I havn't done the EGR mod. Thanks.
Joffo

 

[tweak'e]

i've only quickly read through this......
but the screech is probably from the broken egr bolt.

the egr and exhaust bolts are titanium and the thread pick up really easy ie the nut welds itself to the thread. once you get the slightest movement in the bolt pour heaps of crc etc on and slowly work the bolt back and forth. that will often stop them from seizing.
btw i broke about 4 getting the turbo off.

 

[motoD22]

Cheers again for info everyone. I'm gonna try blocking the egr pipe at the manifold now, as dan-o suggested. Should stop pressure from reaching there. I wont be able to get a good seal on the other end with the broken bolt still. Not sure if this will matter as still havent been able to work out what the thing above the pipe is (3rd picture circled yellow). If anyone knows it would be very helpful. Thanks

 

[motoD22]

ok quick update. ive removed the egr pipe betweeen the mainfold and bit with the snapped bolt. the assembly it went to was stand alone so ive removed it temorarily for a better shot at getting the bolt out. ive attached some pics of it removed, the bit i was trying to find out what it was appears to be some sort of thermal sensor. it is plumbed into the heater hoses on one hose and into the block on the other. a plug goes off the top into the main loom on top of the motor.

Does anyone know exactly what it is and is it still required seeing as there will be no exhaust gases flowing through it after its blocked?

 

[tweak'e]

the bit circled is the egr valve. you will need to leave it connected.
block the egr tube off at the exhaust and intake.

 

[Dave]

A pair of vice grips shoup be able to get that out.

 

[motoD22]

thanks tweak'e. ive got the plate already in the inlet and ive just made up the one for the exhaust ready to fit tomorrow. Am i right in assuming that there will be no pressure at all in cast block in the above pics after blocking? if so i may just make a plate for looks and leave the broken bolt in. Ive hit it with anti-seize, heated it with a blowtorch for 15 mins and got the vice grips onto it and couldnt get it to budge

 

[1310/71]

When you say anti-seize, what exactly did you use?

I've heard good things from an aerosol product called "Yield".

It can be expensive and hard to come by, but if it works........

KB

 

[motoD22]

Hi mate. Yea I was using yeild actually. We have it at work. It's pretty good stuff and usually works a treat. Just no luck this time unfortunatly