Boost leak testing and results

[bazibbo]

So...

I've spent the last year slowly transplanting my 1914 EFI turbo from a swingarm bug, to a 1302, and I've just recently got it back on the road

After a disappointing run or two at my local drag strip, I've now got the time to test and tweak things. I'm getting a high pitched whistle that sounds just like electronic radio interference, but my radio's not wired up, so I'm more than aware that it's a leak.

I'm getting my 14psi, but the car's sluggish, slow to spool, and I'm having engine heat problems as I seem to be running oil temps around 105 - 110 deg C. ( Initially blaming my two vent 1302 engine lid. )

So I popped down to our local hardware store ( B&Q in the UK ) and picked up a few plastic bits of plumbing that would block my 65mm inlet, a bit of tube with a tyre valve grafted on and a cheap bicycle pump. I also filled a squirty water bottle with diluted washing up liquid



I then blocked off my inlet and joined the pump into a T piece between manifold and dump valve. Then got busy pumping, and squirting...



Results

I could instantly hear a 'hiss' from the left side manifold, as expected, but I could also see plenty of bubbles forming on various bits - in fact all over

It leaked from:

Dump valve - I'm not convinced it wasn't simply because the throttle plate was closed, and it was doing it's job, but I've taken it off for now and replaced the dump T with a straight tube.

Turbo - a few bubbles from the cold side around the back of the compressor, not the outlet - I've no idea what to do about this, it might not be an issue as it's at the very front of the induction side and I guess arguably not pressurised.

TPS on the throttlebody - I pulled the seal and gave it a thing coat of a copper RTV silicone stuff that I seem to be using everywhere nowadays!

Air temp sensor - a the back of my top T - my bad tap work Plenty of ptfe tape sorted it

Left manifold - found that the gasket had blown out - it didn't look like that before it went in, but it was a used gasket ( I know! ) I've cleaned the faces and used a thin sliver of the RTV silicone sealant - something I wanted to do before. The right hand side manifold was fine, but I will remove the gasket at some point in the future.



manifold spindle blanking plates - my 2 manifolds from VW Speedshop in the UK could have had throttle body spindles in them - I'm using them as manifolds only. 3 of the 4 blanking plates were showing a few bubbles so I gave them a bit of silicone. I'll do the fourth one when I remove the gasket later in the year.





So that was it - can't hear no hissing anymore, there's a few internal bubbling noises bit that appears to be all, though I can't check the interior pipework as I was on my own and the system wouldn't hold pressure for more than a few seconds. I'm hoping that's because there's always an exhaust valve open, though I read somewhere that it should hold pressure for a few minutes

I'll do the interior pipework - pressure sensor and boost gauge later - I'll simply pull the interior inlet pipe off and stick my pump on there.


So has it worked?

No idea - only did it last night and it's raining here in East Yorkshire, I'll report back in a few days but would love your comments / advice

[andy198712]

thats a fair few leaks! hope it makes a difference! with a valve thing, if the inlets are closed it should be ok and hold pressure better? are they all closed at some point?

[Volky]

Hope you solved all your leaks. I also have a fairrrrrr amount of leaks I guess since I'm getting those symptoms in the car. I don't even get boost in first gear. All you hear is a type of whistle which sound nice but no power. I prefer to get the power than the whistle. I was thinking of doing the boost test with a compressor, too.

Good day.

[bazibbo]

thats a fair few leaks! hope it makes a difference! with a valve thing, if the inlets are closed it should be ok and hold pressure better? are they all closed at some point?

Me too Andy

I've got some rocker gaskets on order - I might redo it with the covers off, noting the inlet positions - though a seat of the pants test will let me know how things are going.

Hope you solved all your leaks. I also have a fairrrrrr amount of leaks I guess since I'm getting those symptoms in the car. I don't even get boost in first gear. All you hear is a type of whistle which sound nice but no power.

I'm not certain how 'efficient' that test it is, but it's certainly cheap, easy and quick to do. I'm hoping someone will come along and give me a few more pointers, such as sticking a tennis ball up the exhaust and being able to pressurise the exhaust as well.

[andy198712]

If your take the covers off, two more bolts and you got the rockers off, all valves closed.... Well 4 bolts total

[Dan Dryden]

Andy has suggested exactly what I was thinking! Take the rockers off and do the test again.

I think your biggest leak was from the inlet manifold gasket. Mine used to blow out every few thousand miles when I ran dual Dells. The tell tale sign was lots of popping from the exhaust on the over-run.

[Piledriver]

Andy has suggested exactly what I was thinking! Take the rockers off and do the test again.

I think your biggest leak was from the inlet manifold gasket. Mine used to blow out every few thousand miles when I ran dual Dells. The tell tale sign was lots of popping from the exhaust on the over-run.

Might want to run the flange of the manifold on some wetordry over a bit of plate glass or such.
They frequently aren't flat once used even briefly esp with a thick compressible gasket.
Much better to get it so flat that its like metal on metal.
The anerobic Permatex sealant for cases works well for a LOT of things and is ~infinitely easier to clean off than RTV.
The thinnest smear of the stuff works, and if a little spooges out it will not cure and form snot balls like RTV.

[bazibbo]

Good thinking lads - I'll give that a go.

This the one Piledriver?


I'll get some bought - thanks

[risk]

I cut my own gaskets from some Napa gasket material. It's cheap and have never had one blow out. I use a hollow punch for the bolt holes, bolt the gasket onto the intake, then cut out the intake holes with an Xacto knife. Works for me!

[Piledriver]

No, that'll work if the surfaces are perfect but it never sets.
This:

[bazibbo]

Thanks Piledriver - found the very same product on ebay UK and I've got it ordered.

I had a short run out this weekend, the first since the leak fixing. Initially things were a lot better, pulling at 10psi a whole lot better than it was at 14psi last week, but it still had the high pitched whistle and was feeling and sounding odd by the time I got back home.

On shutting the engine down, despite idleing for a bit, it sounded like a jet shutting down as the compressor wheel was, I guess, rubbing on the housing. Rebuild time

I suspect it wasn't happy with being stood for a year.

[andy198712]

Oh poo