Help! Strange whistle at max boost!

[Timbo]

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]

Found this pic of a GQ RD28, have highlighted the valves location in the bottom right corner of pic;



Tony

[Timbo]

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]

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]

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]

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]

Well if thats the culprit Timbo then thats good news mate!

Keep us updated for sure.

[MudRunnerTD]

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



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.