How squashy should intake pipes be?

fishsponge · Dec 12, 2010

Most of the pipes that the air flows through to the turbo, from the turbo to the intercooler and from the intercooler to the intake manifold are pretty rigid.

One of them, however, at the bottom towards the back of the engine bay (which takes a 90 degree bend) is very squishy indeed.

If the pressure in that pipe is always positive, I don't suppose it matters much, but if there is ever a negative pressure (i.e. a vacuum) it will theoretically suck flat very easily.

I'd love to test this out, but it's pretty hard to put the engine under load while looking under the engine bay!

So, I guess my question is this... do I need to replace that pipe, or does it not really matter??

I'll try to give a more accurate description when it's not pitch black outside!

hughesy · Dec 12, 2010

It's fine. Squash the top one between the turbo and the intercooler with one hand then rev the engine with your other. It'll stiffen up alarmingly when the boost kicks in. Unless your turbo doesn't work of course.

fishsponge · Dec 12, 2010

well that's not the one that's squashy... the pipes to and from the intercooler are pretty rigid actually. it's the pipe that does a 90 degree bend at the back of the engine bay... i can't remember what it goes to and from off hand though...

davek0974 · Dec 12, 2010

Sounds like the turbo inlet, from air box to turbo. That one is. Prime candidate for delaminating and blocking the turbo, especially if the air filter is blocked, naturally we don't let the filter get blocked do we

fishsponge · Dec 12, 2010

OK, i've been outside (pretty cold!) and photographed it! See the attached photo.

The squishy pipe is the one at the back that does a 90 degree bend. The turbo and exhaust are on the left.

You say it sounds like the pipe from the airbox, but I think it's below that one.

Brian S · Dec 12, 2010

That looks like the turbo to Intercooler pipe (Small radiator next to main radiator)

It will be flexible compared to the straight part which should be rigid,

Its under pressure so should not have any splits or leaks.

fishsponge · Dec 12, 2010

it does look like it goes into the bottom of the intercooler actually.

I assume, therefore, that if the turbo is compressing it is at positive pressure, but if the turbo isn't compressing, it's at negative pressure.

And yes, it is flexible (very flexible indeed!) and the straight pipe is rigid.

It certainly has no splits of leaks... i was just concerned with it being sucked flat and restricting airflow...

Brian S · Dec 12, 2010

It will be under pressure. if it is too squashy then it may bulge under pressure.

If you think its getting past its best then change it. I dont know how much they are but cant be much for peace of mind.

Are you having some turbo related issues then?

Brian S · Dec 12, 2010

Have you compared it with the engine running? Perhaps squeaze it while someone gives the engine a rev and see if you can feel it presurise.

(I rewrote that last word a couple of times as I don't want anyone feeling they need to quote something out of context.... lol )

fishsponge · Dec 12, 2010

Brian S said:
It will be under pressure. if it is too squashy then it may bulge under pressure.

If you think its getting past its best then change it. I dont know how much they are but cant be much for peace of mind.

Are you having some turbo related issues then?

well... not to my knowledge... i've only owned a Landy for 3 months now, and never looked after anything more complicated than a single cylinder motorbike engine prior to this though, so who knows.

I've no idea if I have turbo problems or not... probably not, but i've only ever driven one diesel vehicle in my life and i've only ever drived one vehicle with a turbo in my life, and it's this one!

I was applying simple logic - pipes that deal with air shouldn't be too squishy. If they are squishy and in a vacuum, they will crush down and restrict airflow. I was therefore wondering if I could improve anything by replacing that particular pipe.

Given that it's only ever under positive pressure though (as my understanding from the above conversation), the worst it'll do is bulge.

Could I get the turbo up to full pressure by revving it while stationary in neutral? That'd allow me to see if it was bulging or not!

In summary... i'm trying to do everything I can to make my vehicle run at its best and have very little knowledge of engines at this stage!

Brian S · Dec 12, 2010

If it aint broke dont fix it...

You wount get much pressure just revving the engine, it needs to be under load (Driving) but if you have not got any smoke you should be ok.

I know how you feel, I do have 26 years of messing around with cars as a hobby but I am on my first TDi Discovery (Had a V8 Last Winter) and I have learned loads from this forum.

I brought mine on a budget and had loads of issues to sort out, but after 3 months the truck is now running as sweet as it should.

I am not 100% about the Auto box and the Timing Belt needs doing as soon as the funds are there.

But if you use your gut feeling about whats not right and get things fixed as they need doing you will have a Landy to be proud of.

fishsponge · Dec 12, 2010

that's kinda what i've been doing... i've been adding stuff to my wishlist as I decide i want stuff too, for either myself or someone else (!!) to buy.

I think I'll wait until the next pay & play day and then ask if I can squeeze someone else's intake pipe!

ginge1100 · Dec 13, 2010

pay and play day is one thing but i dont know how i might react if you ask to squeez me pipe,think you might have gotten the wrong idea about these events.lol

Brian S · Dec 13, 2010

fishsponge said:
that's kinda what i've been doing... i've been adding stuff to my wishlist as I decide i want stuff too, for either myself or someone else (!!) to buy.

I think I'll wait until the next pay & play day and then ask if I can squeeze someone else's intake pipe!

If your feeling inadequate then comparison with others can help.

I am not modifying mine, just fixing things as they break and that keeps me busy enough.

davek0974 · Dec 13, 2010

Its good that you are checking things out but that pipe should never really be at negative pressure (vacuum) as the turbo is always spinning albeit at different speeds.

fishsponge · Dec 13, 2010

I held the pipe while revving the engine this morning (got my work shirt covered in crap!) and i never noticed any change really. Having said that, the turbo wouldn't be working while the vehicle was stationary, so in summary - everything's probably fine!

And yes... i do know what pay & play days are for, and it ain't that!

How squashy should intake pipes be?

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