Wastegate blowing open? (1 Viewer)

[Feistl]

Hi Everyone,

Finally got my 80 series 1HD-FT up and running however I am having a few issues with the turbo.

Just for some background info... I have fitted a 3" stainless exhaust system including high flow dump pipe, fitted a late model 1FZ airbox with new filter and a large water to air intercooler. The turbo is a Mamba TD05H 16G... I fitted it with the 18psi rated spring in the wastegate (as that is my intended boost pressure) however it seems to make around 10-11psi with an airline directly connected.

I fitted a turbosmart boost controller which i have been able to adjust the pressure up to around 15psi however regardless of how much more i screw the adjuster i can't make more than 15psi boost. So i disconnected the wastegate hose completely and took it for a drive and still only managed to see a peak pressure of 15psi (Maybe 16psi briefly, but settled back to 15psi). This is pretty much from about 2200rpm up to 4000rpm.

I am just wondering if the wastegate is being blown open by manifold pressure and if that's because the wastegate spring just isn't strong enough OR if there's not enough preload?

If the current spring is actually operating around 10psi would using a boost controller be ok for a target of 18psi? Or should I change the wastegate spring to something stiffer (which requires pulling the turbo out and is a pain in the ass job with the other mods I've done). Being a diesel I'm not too worried about boost creep or surges (as the turbo should be capable of running over 24psi while still being pretty efficient).

Cheers,

 

[KiwiDingo]

Just do a quick check of adding more preload, how many turns do you currently have? Depending on what turbo you choose you might need anywhere from 2-10 full turns of preloaded. If that makes no change in peak boost then you most likely don't have enough fueling, what AFR are you running at this 15/16psi?

 

[Nz Nath]

If you can get to it, you could also try wiring the gate shut. You might not get it to stay fully closed, but if it makes a difference then you know your wastegate spring is too weak.

My experience with one of those kinugawa/mamba wastegate actuators was that they're way off on what they prescribe the springs to be good for. I ended up fitting the stiffest spring they did. My memory is a little hazy, but I think I had the problem that you're suspecting, the spring couldn't hold shut against emp even with the boost line disconnected.

 

[Feistl]

Just do a quick check of adding more preload, how many turns do you currently have? Depending on what turbo you choose you might need anywhere from 2-10 full turns of preloaded. If that makes no change in peak boost then you most likely don't have enough fueling, what AFR are you running at this 15/16psi?

I went with “half a hole” of preload as recommended, but wondering if that isn’t enough. I will add more preload, just wanted some feedback before doing it as it’s a tricky job...

AFR will be super lean as I haven’t increased the fueling yet (waiting for a timing tool to adjust timing first). At full load in 3rd gear going up a very long/steep hill Max EGT I’m seeing is just under 400 degrees C.

i didn’t realise this could make an impact as well...

If you can get to it, you could also try wiring the gate shut. You might not get it to stay fully closed, but if it makes a difference then you know your wastegate spring is too weak.

My experience with one of those kinugawa/mamba wastegate actuators was that they're way off on what they prescribe the springs to be good for. I ended up fitting the stiffest spring they did. My memory is a little hazy, but I think I had the problem that you're suspecting, the spring couldn't hold shut against emp even with the boost line disconnected.

Thanks, might try wiring the gate shut as that’s probably easier to do.

I am annoyed I didn’t fit the heavier spring, just didn’t want it to be overboosting so figured the 18psi spring would be pretty close so the manual boost controller would give me fine control. But if it’s opening at 10psi is obviously a bit too weak...

thanks for your help guys .

 

[KiwiDingo]

If you can't get enough tension on the gate using wire as it's a terrible spot to try and work around I've previously used some big industrial cable ties which will last long enough for a few test drives before the heat melts them and break. Using the cable ties also allows you to put enough tension on the gate to hold it completely shut which can be difficult with wire.

 

[Feistl]

Hey guys,

I followed KiwiDingos advice and tied a cable tie around the wastegate (still a crappy job) and took it for a drive, still only seeing 16psi (maybe 17psi, but hard to tell).

There is only one rubber joiner between the turbo and intercooler with proper silicon hose clamps, i tightened them up even further but again no change in max psi.

Only other area it could be leaking boost is between the intake manifold and head? (Ill check the bolt tension tomorrow).

Any other ideas what could be causing boost to stop climbing? It seems to get to 16psi pretty quickly with the wastegate cable tied shut (faster than before by a bit) but still limited to max boost...

Is it just a case of needing more fuel? (I would have expected boost to keep rising regardless of actual fuel load).

Cheers, Errol.

 

[Nz Nath]

How confident are you that the gate isn't still able to open slightly? It can be hard to get all the slack out of cable ties, and they normally have some give in them. The fact that spool up happens faster than before tells you that the wastegate was opening under emp alone below your target boost pressure. So you need to do something with the wastegate actuator no matter what, even if something else is hampering boost.

 

[IanB]

Another suggestion, and easier than adjusting pre-load via the wastegate, is to add washers to shim the wastegate actuator away from the turbo which has the same effect as adding pre-load. I use a bicycle pump to open the wastegate actuator and hold it open, then loosen both actuator bolts, but remove only one at a time, and using a magnetic "dropped bolt" tool I position the washers and put the bolt back, then do the other one. It's still a PITA to do, but will confirm if adding pre-load provides the desired effect as I'm guessing you need to pull the turbo to make wastegate adjustments.

 

[Feistl]

Hey guys,
Well spent ages stuffing around pulling the waste gate out (pain in the butt) and changed the a heavier duty spring and have it more preload, but same result.

tried a bunch of different cable tie options but couldn’t get any more boost.

I tried changing boost gauges and did a test with a radiator pressure tester and confirmed both gauges and the over

so decided to have a look for boost leaks, this is a pain in the butt as the turbo inlet has been modified with a welded/fixed piping which includes ports for the catch can return and barb for the York 210 compressor.

Anyway eventually was able to try and pressure test the system but really struggled to even get to 10psi on the gauge, and that’s pumping in at nearly 100psi....

So turns out the intake manifold gasket (between the manifold and head) is leaking like an absolute sieve lol. With manifold pressure at 10psi you can literally feel a breeze over the entire length of the manifold and see the air rushing out (little droplets of oil are spitting out).

I tried tightening the bolts a little (the ones I could get too) which helped fractionally, but clearly time for new gaskets...

so yeah, my mistake for dismissing it initially as I figured they would hold pretty well.
Just trying to decide whether to go genuine or after market gaskets...

anyway I will post back once I’ve changed gaskets. Thanks for your help guys

 

[IanB]

Genuine for sure for the IM to head gaskets. I've done this job, you need to remove all the injection pump to injector hardlines, so it's super important to keep that all straight for when you go to put it back together. You might want to plan on cleaning out the IM while it's off as well, it's bound to be full of oily crap from the factory valvecover vent.

 

[Feistl]

Quick update...

Finally got around to pulling the intake off, the gaskets were rock hard and the nuts weren’t even finger tight... like loose on the stud.
Amazingly the intake manifold is sparkling clean, only a tiny bit of oil film but overall very clean.

also I suspect the engine is in pretty good condition as there is very very little blowby (Eg with the engine running if I put my finger over the vent tube for say 10 seconds and then release there is a very small amount of air build up, like 1-2psi tops.
I’m just contemplating whether I should change the valve stem seals as well...