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Timbo
16th July 2010, 04:05 PM
Hi Patrol nuts, (LONG POST)

I've had this problem for quite some time now and it drives me crazy. I've asked around on different forums and still no solution. Hopefully one of you Patrol gurus can give me some insight.

What happens:
When the car is warm (after about 15-20mins of driving) a separate whistle sound emits from under the bonnet. It's not the normal Turbo whistle, it's louder (not fan belt screeching loud), more like a kettle. It's hard to explain. The sound does not occur until max boost, or just under. If max boost is 12psi, I'd say it's happening around 10-11 psi.. in any case, it's right toward the end of the boost limit.

Again, this is a separate whistle sound from the normal turbo whistle.

What I've done:
This has been happening for some time as I said. It's getting harder and harder to remember when it occured. I remember blocking the EGR valve for the first time and then it appeared. I've only made this assumption a while afterwards though.

Originally I thought it was because I squirted WD40 onto my fan belt and I thought it was squealing through slippage.

I've since changed the blocking plate to stainless steel, thinking that aluminium might have been too soft under the heat and warped. Unlikely I know. There appear to be no leaks around the seal.
I have taken the plate out as well and left it standard, only to have the sound still there!

I have blocked all of the rubber hoses off leading to the EGR, taken the butterfly out of the intercooler and blocked the hoses to that, I've tightened up all of the intercooler hoses as far as I can as well.

What I haven't done:

I haven't checked the exhaust manifold or around the waste gate. It could be something to do with the headers not sealing to the block.. but I find it unlikely because this happened to my VL commodore RB30T and that's a really really loud screeching sound.

My Thoughts:

It doesn't happen when it's cold. To me, it's like something is expanding when the motor gets hot and is breaking a seal. Maybe a gasket? It's definitely pressure related. I can virtually make this happen on command in 3rd gear at about 3000rpm (im guessing because my tacho doesn't work :( another issue!) I can literally accelerate and make the noise appear, then just let off the pedal and it'll go.

I was told that if it was the EGR, if I press the accelerator to the floor hard, then the noise might go away because the EGR shuts off or stops working when under full acceleration. When I tried this, it didn't work. But sometimes, I have noticed under full acceleration the noise does go away all of a sudden. It'll be making the stupid loud whistle sound, then just stop.

My GF said it sounds like it's coming from the snorkel. At this stage, I'm willing to try anything, however silly it may seem. I might fiddle around with the snorkel on the weekend.

It still sounds EGR related to me.. or in that area. I'm buggered if I can figure it out.

What do you guys think?

patch697
16th July 2010, 07:07 PM
Your right....thats one long post but top effort detail is good when using chat rooms. You just left one bit out..... What are we talking about here:

What model?

What engine?

Is it inter-cooled?

This info would also help..



Still a top effort well done

Cheers
Paul

Chris60
16th July 2010, 07:27 PM
Can't help out with the question but i saw he has a 2.8td GU 1999 wagon on another thread if that helps anyone.

Timbo
16th July 2010, 08:02 PM
Yeah sorry Patch, you're right, where's the info on the car.

2.8td GU 99 model intercooled

YNOT
16th July 2010, 08:03 PM
Just an idea, 2.8's and some 4.2's had an over pressure boost relief valve on the inlet manifold. Normally these valves open between 14 and 16psi, but the spring in yours may have weakend and be opening earlier. Try cable tying it closed and go for a drive.
If all else fails, put your car on a chassis dyno. Your noise seems reasonably consistent which will make it much easier to replicate.

Tony

Timbo
16th July 2010, 08:13 PM
Thanks Tony for your reply.

You just reminded me and I forgot to mention that I was going to ask if anyone knew if there was a boost relief valve.. I thought about the one on the VL and how I blocked that off when I got it intercooled and increased the boost.
I will search for that tomorrow and have a scratch around.

I put the 4wd on a dyno not long ago but they said they didn't hear anything at all and that any sound I might be hearing is the wastegate.. apparently they sometimes do that. I walked away shaking my head thinking... you guys really don't even care at all. They got their $180 and are happy.

cheers

Timbo
19th July 2010, 08:48 AM
Hi Tony,

You don't know where the boost relief valve is on the 2.8td do you?
I had a look through the manual I got off this site and it didn't list one. I know where the one is on the VL, it's on the plenum near the throttle body.. but I can't seem to find it on the GU.
Any ideas?

YNOT
19th July 2010, 09:55 PM
I was fairly sure all RD28's had them, but I may be wrong. If it's there, it will be on the plenum somewhere.

Tony

Timbo
20th July 2010, 08:14 AM
Alright.. i wasnt sure if they had them or not. One would assume that any turbo car has a relief valve but with diesels i dunno. I'll take another gander at the plenum and see what i can find.

GU89
20th July 2010, 05:15 PM
Dont know if it will help but the over pressure valve on my 4.2 was on the crossover piping going into the inlet manifold.

Timbo
20th July 2010, 10:14 PM
2.8's don't have an intake crossover pipe and it seems they don't have a boost relief valve either.

Been right through the manual, it would be there if it had one, for sure.

One of those problems I'm likely to never find a solution for methinks!

YNOT
22nd July 2010, 09:08 PM
Found this pic of a GQ RD28, have highlighted the valves location in the bottom right corner of pic;

http://i758.photobucket.com/albums/xx224/tonyh01/RD282.jpg

Tony

Timbo
22nd July 2010, 09:41 PM
Wow that looks so much like a 3.0 nissan petrol motor. Are you 100% sure that's a 2.8? It's the same rocker cover on my VL.

In any case, the 2.8 diesel in the GU looks quite a bit different and I can't find any item like that on the motor.

YNOT
22nd July 2010, 10:15 PM
That's definately an RD28, you can see the injector pump and injectors on the LHS. If it looks like an RB30, it's because they come from the same engine family. RB series engines bolt straight up to the same engine mounts and bell housing as the RD28. Replacing blown RD28's with RB25/RB30's is quite common.

Tony

Timbo
22nd July 2010, 10:48 PM
Cool, I didn't know that. Good to learn something new although It's a bit late for my brain to take it in haha.
The whistle just taunts me every day though.

It must also be heat related because there's no sign of it until the car is hot. I can start the car up and take off within seconds and be at full boost in 1st, 2nd, 3rd and it's fine. As soon as that temp climbs to about half way, you can count on it singing it's little whistling tune. Bloody annoying.

Timbo
26th September 2010, 03:03 PM
UPDATE:

Well, I THINK I may have solved this gremlin finally!

I started to take my EGR off yesterday morning and for anyone who doesn't know, you need to take the manifold off, or at least, slide it back a bit to get the EGR unit off because it hits the rocker cover.

I started undoing the manifold bolts and thought they were pretty damn loose.. requiring very little effort to undo.

Unable to actually shift the manifold.. it's really stuck, I decided i'd take off the rocker cover instead. That idea failed as I couldn't get to 1 bolt which was under a rubber hose. The hose started to split when i was trying to remove it. I was running out of time (grand final day..ppl were expecting me) so I put everything back together. I tightened up all of the bolts.

Took it for a run today, got it nice and hot. No strange whistling noise now!! I'm HOPING that it was simply air leaking from the manifold because the bolts weren't tight enough.. which would probably make some sense!

Finger crossed this is the end of my strange noise woes. BUt I have actually got another noise appearing now so i'll have to get the mechanic to look into it when it's in for a service. Seems to me clutch orientated :(

Will update again when I think i'm 100% positive I've solved this problem.

Cheers

AB
26th September 2010, 03:08 PM
Well if thats the culprit Timbo then thats good news mate!

Keep us updated for sure.

MudRunnerTD
8th October 2010, 07:40 PM
If it was a loose manifold bolt wouldn't you be getting excessive exhaust noise? or are you talking about the inlet manifold? Sorry know nothing about a 2.8, TD42s are my thing.

Interestingly, i have just blocked the EGR on the GUIV TD42Ti and added a manual Boost controller then put it on a dyno before the big trip.

THe Manual Boost controller i used was one of these

http://www.nissanpatrol.com.au/forums/images/imported/2010/10/6.jpg

Note the tube off the boost controller to Vent to engine bay, well after going on the Dyno and putting in a max boost of 14 i now get a bit of noise on full boost exactly like what you describe. Exactly. I immediately assumed it to be "blow by" through that hose when Max Boost is achieved and i have disregarded it. As soon as you back of a whiska (drop the boost) it reduces to nothing. not like switching a light on and off but rather wind on and wind off the top 5% of the boost i reckon.

Do you have a controller like this? If not then a Factory Max Boost Blow off sounds like a very likely cause.

Solution? Wind back the boost? Block the valve? Extend the vent to under the car and down towards the back into "who cares i cant hear it" World?

Your on the right track.

Hope this helped and good luck.

MR.