Turbo/Boost Problem

[peruccy]

Hello!

First, let me introduce myself. My name is Dejan and I come from the EU, Slovenia to be precise. I have been visiting this great forum for some time, but haven't had a chance to register and post something useful, until now.

The thing is, I have a problem with my car, err more specific, with my turbo. Since I don't own a DSM, I know this might not be the best place to ask, but I do have a similar turbo to the stock DSM one - TD05H-12B.

I did an engine swap about 6 months ago on my alfa romeo 145. I took out the stock 1.8 and put in a v6 turbo unit, from an alfa 164. The engine in the 164 was completely rebuilt, prior to the swap. But since the swap, I've had low boost issues. I have really tried everything I could think of, to no avail. I'm running out of ideas guys.

What I've done so far:
Firstly I bought a new boost gauge (I've already tried two gauges with no luck). Then I swapped the stock bosch dump valve, with an adjustable one (bosch unit had a broken membrane). After that, I found that my wastegate actuator rod acted strangely (it was moving way too much). So I purchased a forge unit for a sierra cosworth (mainly because parts for an old alfa, are impossible to get in my country). Recently I bought a big 16G wheel and compressor housing and a full rebuild kit. So basically the turbo should be spot on. I also replaced all the vac/boost lines with brand new ones. I have fitted an MBC (left the stock electronic valve plugged in, but blocked off the lines). I did an intercooler leak test with a compressor and it held 2.5bar (37psi) of boost for 15min without any leakage. I also replaced the throttle body, triple checked all the sensors with the workshop manual and everything is in the tolerances...

My problem is like this... At idle, I get normal vacuum readings, but as I accelerate, the gauge jumps from cca -0,7 to -0,2 and then slowly goes above 0, to about 0,5bar (~7psi). And I mean slowly - boost is rising so slow, you might think, something was blocking the flow. I could record the gauge, if that would be of any help. I do hear the turbo whistling/spooling. There is also no noises coming from the engine, that would suggest exhaust leak/boost leak (checked both about 5 times now). When I rebuilt the turbo, I did however notice a crack in the wastegate (but after some research, almost every TD05 has a crack there).

So my question is... what else could I check? Could the WG crack be at fault? Is there a small leak, that I've missed? Turbo now, with new bearings has virtually no shaft play whatsoever. Almost everything is brand new, what else could it be?

BTW, here's my car, so you wouldn't think I'm making stuff up:

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Thank you in advance for any info. It is much appreciated!

Edit: I almost forgot... Stock boost for this engine should be 0,9bar (~13psi). Also, if I rev the engine at idle, I don't hear the turbo whistling/spooling and the boost gauge goes up to 0 (no DV noise either). I only hear the turbo when I'm driving, if that helps...

'talla

 

[stefanOst]

Have you done an actual boost leak test? Leaks can be coming from places you would have no chance of seeing just by looking it over


Cool car by the way

 

[TSi Kid]

check if you have any exhaust leaks, maybe your manifold is uneven and not causing all the exhaust to spool the turbo.

 

[peruccy]

@stefanOst: Thank you! No, I haven't done an actual boost leak. I only replaced all the clamps and re-tighten them as hard as possible. I have made a home-made "tool" for IC leak testing though ->

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And it held ~37psi for 15min

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... so could I make another "tool" for boost leak testing? Or what would be the easiest way to test boost leaks? Because I'm not sure how much air I could pump in the system, without doing any damage...

@TSi Kid: When the engine was rebuilt, I also did some work on the cylinder heads

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And on various other components

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... So it should pretty much have a good seal. Anyways, wouldn't I hear a loud squeak if the exhaust gases were escaping before they can spin the turbine?

I'm more concerned about the WG crack. Before it was like this ->

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And then I enlarged the WG hole a little bit. Now it's a little better, but I still have concerns ->

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Or is that acceptable? I do hope my exhaust manifolds are sealing, because taking of the 1-2-3 exhaust manifold is next to impossible, without pulling out the engine :\ So any more ideas what I can do/check, before I go and check the manifolds?

 

[TSi Kid]

That wastegate crack is your problem.

 

[Rockyp]

I agree that the crack would be a problem. Great job with switching that engine. That 2.0 V6 was one of the first to have variable valve timing with a turbo option. I had an engine similar to that in my Alfa 156 i had a few years back when i lived in northern italy.

 

[peruccy]

Thanks guys! I will take it apart, again :\ Hopefully my problem will finally be solved...

 

[dented_coffee]

Have you inspected your vac hose that runs to your boost gauge? what brand is your boost gauge and what year was it bought?

There could be a kink in the vac line and thats why your gauge isn't reading correct or as accurate as it should.

The crack will not affect anything really. The hotside on my 1994 talon was basically melted and there was a gap big enough for me to put a #2 pencil threw with the flapper closed. It still spooled almost as fast as it normally would. Is your WG flapper able to completely seal all the way around the diameter of the hole that is now ported?

 

[peruccy]

@dented_coffee: Vac lines are almost new. Bought them ~2 months ago, complete with new small clamps all around. The boost gauge is in fact brand new, got it last week, it's an RaidHP gauge (I think it's german).

Yes, I didn't exaggerate with the WG hole. I made it just a little bit bigger and smoother. The flapper has about ~1mm edge all around, when closed...

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Well if the crack isn't the problem, I don't know what is. I took off the pipe from turbo to IC today, when the car was running. Applied some throttle and there was no hissing noise or anything like it. It's like the turbine can't spin the compressor enough, at low revs. Perhaps that is why I only get a slow rising 7psi (instead of 13psi) when at WOT in 3rd,4th,5th and ~3psi in 1st,2nd. I presume that then, the turbine is spinning so quickly, even if gases escape, most of it manages to spin the compressor. What do you guys reckon?

I'll re-check all the vac/boost lines again. Take the turbo off and inspect it and check that the exhaust manifolds are sealing properly. If that won't fix the problem, I don't know what will...

 

[dented_coffee]

I know that the vac lines are new. I read every post on here before I posted. I do that with just about everything that I give input on. It's nice to know whats going on before I go rambling on about something that could be completely wrong .

What I was saying is that the vac line running to your boost gauge (i assume its not an electrical gauge). That vac line running to it might of gotten pinched, cut, or bent and its not allowing it to read as precise as it should. I have seen it happen before to where the vac would read but the psi would be slow with readings until at higher levels. Thats why I said it because I have personally seen it.

Sorry for confusing you if I did. I was just throwing my 2 pennies in on your situation in hopes of helping get your issues worked out on it.

 

[95redturboawd]

Having this same problem with my 16g. Hopefully someone can chime in. My boost gauge is fine, if we're having the same problem you could tell it's boosting slow without a gauge.

 

[peruccy]

@dented_coffee: Sorry, I didn't mean any offense. I appreciate all the info on the matter, don't get me wrong. It's just hard to imagine my vac/boost lines to be the culprit, since I was very careful when installing them (mostly when I was pulling them through the firewall). I've also tried two different gauges and I've also tried running the gauge directly from under the hood to the gauge through an open window - result was the same...

I've read that some turbos, when rebuilt, won't spin at idle without load until the bearings wear in a little bit. I did the rebuild ~2 weeks ago, before I got the new gauge and I haven't really driven the car much. But what if the turbo doesn't whistle when applying some throttle when the turbo to IC pipe is removed? I can remember my previous turbo car, when the IC pipe was removed, I could hear a loud whine, even at idle...

I've checked around the turbo again, for any obvious leaks (very little space to see things clearly). I found some carbon remains, but I'm not sure if that is it, or not. It's on the turbine housing side, where the exhaust elbow bolts on. Could it be that, or isn't that already part of the exhaust, so it shouldn't interfere with spinning the turbine?

If that isn't it, I've got another long shot option... The wastegate actuator is from a cosworth - for a T3 turbo. It has a very strong membrane (almost impossible to move the rod in & out with hand). Could that be the problem? So my small turbo can't operate that WGA?

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Another long shot option is, I've made a hash when rebuilding the turbo, or that my turbine shaft and/or my turbine wheel, are too badly worn out (even though both looked fine and had no marks or dents). What do you guys think? If it helps...

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I'm ready to try anything. BTW... thanks for all the help so far!

 

[95redturboawd]

Mine was recently rebuilt too, it's got about 1,800 miles on it now. Hardly any of it was in boost. Hmm. I think if the wastegate actuator was too strong, then you would get too much boost. If it's too strong that means it takes more pressure to open it, so basically the opposite problem we're having.

 

[peruccy]

Mine was recently rebuilt too, it's got about 1,800 miles on it now. Hardly any of it was in boost. Hmm. I think if the wastegate actuator was too strong, then you would get too much boost. If it's too strong that means it takes more pressure to open it, so basically the opposite problem we're having.

So your gauge also shows slow rising boost? What about my other problem, that I can't hear the turbo whistling if I take off the turbo outlet pipe. You have that problem as well?

I've basically narrowed it down to an exhaust leak somewhere, or a worn turbine shaft. Can someone please confirm, that these are the correct specifications for a stock TD05H turbine shaft?

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Even though mine looked in great condition when I did the rebuild, compared to the shaft of another turbo I have at home, which had seized bearings - the shaft was completely worn, you could tell just with a finger.

@95redturboawd: If you find anything out, do please let me know. We might have the same problem...

Edit: OK... I'm 99,99% sure, I've found my problem. I Lifted the car on the ramp and immediately after I turned it on, went underneath and looked for leaks. Manifolds are sealing, but I could see condense from the exhaust, coming from between the turbine housing/turbo elbow. Looks like I'll need to have both parts machined/straightened and a new gasket. When it's done and tested, I'll report if that fixed my problem once and for all.
Oh... and my compressor wheel is spinning at idle, so all is good with my rebuild. What a relief

 

[peruccy]

OK, so I've removed the turbo, again. Took my turbine housing and exhaust elbow to a shop for straightening - apparently it was out by 0,02mm. Put a new gasket on, start her up, and... Still the same! Boost gauge behaves exactly the same as it did before, and before that, and before that. Full boost is ~7psi @ WOT in 3rd, 4th, 5th with boost slowly rising to that point. If I let go of the throttle, it jumps down to -1 vacuum (lowest number on the gauge).

Also, turbo is slowly spinning at idle, but I don't hear the turbo whistling, when applying the throttle. Gauge goes to -0,2 vacuum, which AFAIK when opening the throttle, there shouldn't be vacuum in the system. And at idle, the gauge should jump to 0 or some positive pressure... right?. That's puzzling me quite a bit. How can there be vacuum in the system, when I open up the throttle valve...

I've checked around and there shouldn't be any exhaust leaks left (at least none are visible when starting the engine). For the sake of it, since I've already triple checked and re-done everything, I will also block off the pipes that go to the turbo, and do a boost leak test (even though I doubt this is my problem). 2bar (29psi) should be enough, to see if there are any leaks... right?

And if that fails, that leaves me with what? Turbine wheel or housing needs replacing? I don't want to buy a new turbo, when I've already spent ~600$ on repairing/upgrading this one. And I don't want to spend another ~400$, just to find that my problem is still present. Like that WG crack. Some say it's not a problem, others say that it is... so which one is it?

I really don't understand what is causing this. At the beginning of this project - engine was completely rebuilt, modified oil pump, ported cylinder heads, new clutch, machined flywheel, 300lph fuel pump, bigger IC moved to the front, new adjustable FPR, new adjustable DV, new adjustable WGA, free flowing 2,25" exhaust, MSD ignition coil, almost every sensor new. And now, rebuilt/upgraded turbo. Bottom line - the engine itself should be 100%. What more does this piece of junk want from me...

I have nearly twice as much oil pressure, as stated in the engine workshop manual. 6,5bar (95psi) when the engine is cold. Could this be my problem? I've read that MHI turbos don't like a lot of oil pressure... is that true?

Anyone? Please help!

 

[peruccy]

OK, I've done some more tests in the past few days, including two boost leak tests. One was without blocking the throttle body, so I could see if my manifold has leaks. Sure enough, it did - three leaks where the intake pipes are clamped to the manifold. That fixed my rather poor idling at cold start, now I can hear my DV even at idle and I can finally hear my turbo whistling in every gear when driving, not just in 3rd, 4th, 5th as before...

The next test was with the throttle body, breather tank and idle valve all blocked off. This test showed two small leaks on the couplers, which hold the DV in place. All fixed now (I hope!). I will never underestimate the boost leak test again and I will do those two tests periodically each month from now on!

The car feels more alive now, but... those tests haven't fixed my slow rising boost gauge needle. That is why, I still don't know, how much boost I'm actually running. After some research, I think I made a hash when using a T-piece from my DV for the gauge. I can't think of anything else, that could be the problem for it (as seen on this photo)...

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So tomorrow, I'll cut a hole in the intake manifold with new threads and put in another nipple for vacuum source. So all three components (AFPR, DV, Gauge) will have their own vacuum source. That should fix my last problem, right fellas?

 

[JusMX141]

And if that fails, that leaves me with what? Turbine wheel or housing needs replacing? I don't want to buy a new turbo, when I've already spent ~600$ on repairing/upgrading this one. And I don't want to spend another ~400$, just to find that my problem is still present. Like that WG crack. Some say it's not a problem, others say that it is... so which one is it?

Definitely NOT a problem. At least not enough of a problem to make a huge difference. You have to consider the volume of air entering the exhaust housing from the engine....that crack is not large enough to make a difference.

I've had turbos at my shop that were cracked WAY worse or had the flapper hung open / improperly adjusted when I received it and it was working just fine.

I have nearly twice as much oil pressure, as stated in the engine workshop manual. 6,5bar (95psi) when the engine is cold. Could this be my problem? I've read that MHI turbos don't like a lot of oil pressure... is that true?

Absolutely true.

On DSM's and Evo's the MHI turbos are fed at the head (low pressure source) with a .070" restrictor in the line. You should add a restrictor at the very least, and also consider moving the oil supply to a source with no more than 55psi. The way it is you're putting a lot of unnecessary pressure on the seals which will most definitely lead to an early failure.

 

[peruccy]

Definitely NOT a problem. At least not enough of a problem to make a huge difference. You have to consider the volume of air entering the exhaust housing from the engine....that crack is not large enough to make a difference.

I've had turbos at my shop that were cracked WAY worse or had the flapper hung open / improperly adjusted when I received it and it was working just fine.

Thanks for that info! I've never seen that WG crack on a turbo before (CT's, garretts exc.), so naturally I was worried. Well, not anymore

Absolutely true.

On DSM's and Evo's the MHI turbos are fed at the head (low pressure source) with a .070" restrictor in the line. You should add a restrictor at the very least, and also consider moving the oil supply to a source with no more than 55psi. The way it is you're putting a lot of unnecessary pressure on the seals which will most definitely lead to an early failure.

That makes me wonder, why alfa didn't put a restrictor in the first place, if they used a MHI turbo? OK, being italian, they do things their way as always. Where could I get such a restrictor? Hardware store perhaps, or ebay?

 

[peruccy]

Thanks to you guys, all of my problems are solved, except one. That slow rising boost gauge needle. I've tried two gauges. I also ran the gauge from under the bonnet through an opened windows (to see if my gauge line has a small hole - it didn't) and yesterday, I've drilled a hole in the intake manifold, cut threads for the nipple and now my three components (adjustable FPR, DV, boost gauge) have their own vac/boost source.

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You would think, that this would fix my last problem, right? Wrong! I am officially clueless on what to do next... I'm sure, I've missed something - some test, but I can't think of it. There should be no more exhaust & intake leaks. Old & new boost gauge give the same readings...

Anything? Any ideas at all?

 

[ilco187]

What kind of hose are you using for the boost gauge? just my guess if its rubber or silicone it could be expanding with pressure before it reads.

 

[TSi Kid]

What kind of hose are you using for the boost gauge? just my guess if its rubber or silicone it could be expanding with pressure before it reads.

If that doesn't work then you're going to want to check your turbo and you're going to want to check to see if you're getting all your exhaust pressure spooling your turbo.

 

[JusMX141]

Where could I get such a restrictor? Hardware store perhaps, or ebay?

There are restrictors on eBay for use on -4AN lines.

 

[peruccy]

@ilco187: Boost lines are indeed silicone. What lines should I use then? Those clear lines (rubber I think), you sometimes get with a boost gauge?

@TSi Kid: Any suggestion, how to check if all my exhaust gases spin the turbine wheel? I've fixed all my exhaust leaks, is there another test I could perform?

@jusmx141: I found one on ebay. This one is ok, right?
Adapter Fitting M12x1.5mm to 4AN w/ 1.5mm Restrictor on eBay (end time 24-Jan-11 18:19:43 GMT)

 

[TSi Kid]

You're going to want to test for shaft play. Take off the intake pipe and see how much you can move the turbine wheel (in and out, up and down). Also start the car with the intake pipe off and give the car a rev, then turn off the car and see if the turbine wheel is still spinning.

How old is the turbo?

 

[peruccy]

You're going to want to test for shaft play. Take off the intake pipe and see how much you can move the turbine wheel (in and out, up and down). Also start the car with the intake pipe off and give the car a rev, then turn off the car and see if the turbine wheel is still spinning.

How old is the turbo?

I've already answered all your questions before. Read above

- Virtually zero shaft play, now that both bearings are new
- Yes, I already checked and my compressor wheel is spinning when I remove my MAF to turbo pipe. I cannot however start my car if I remove my MAF pipe first. I can only remove it once the engine is running and even then it immediately stalls (old ML4.1 electronics)...
- No idea how old the turbo actually is. But I rebuilt it recently.