Thanks to a response to a post I made ages ago I finally got round to checking vacuum hoses (hiace 3L deisel engine (about 123000km)
I would urge anyone with vacuum hose going to the inlet manifold to pull them and inspect.
On mine a single 5mm hose goes to a t-piece - this hose, the t-piece (with inbuilt restrictor)and the hoses each side of the tee were blocked solidly
Renewed hoses and cleaned out t-piece with WD40.
The egr system I assume is clogging the inlet with soot etc. - so guess this needs checking at each service
(Not sure why crud was sucked into vac system though as the manifold has vacuum)
Anyway nothing earth shattering happened performance wise - but filled up today and have got 20.07 mpg!
Now that might sound terrible to some but its a clear 2 mpg more than I have been consistantly getting and as I have finally broken the 20mpg barrier a minor celebration is in order.
If anyone thinks it should never have clogged in the first place (or the mpg is not related) and it points to a particular prob please let me know -
Chris
- (#8982) Chris Turner, 5 Jun 03 18:03
Consequence of EGR on any diesel I'm afraid :(
- (#8983) david miller, 6 Jun 03 1:01
Cheers Dave - as the crud in the hoses must have been relatively residual - then I would guess the inlet manifold must be harbouring loads of it - and wonder if the inlet valves are getting buried in it? -
Would the heat insulating properties of crud potentially cause any probs with the inlet valves?
Wondering if emptying a tin of carb cleaner through the hole to inlet manifold would have any value?
Or would the engine not appreciate the muck entering the combustion chambers?
Well - lots of questions but I suppose the bottom line is should I take some action or is it OK left alone?
Cheers
Chris
- (#8984) chris turner, 6 Jun 03 9:01
If the manifold comes off reasonably easily, you could schedule it for sometime you're bored...
I know it's a real problem in the US for VW TDIs- an inlet duct about 1 1/2" can be restricted to well under an inch, but their diesel is much sootier and dirtier than ours. A good quality of oil helps too- less fuming, so less for the soot to clag with...
- (#8985) david miller, 6 Jun 03 10:04
Thanks Dave
Thats alot of crud restricting the airways!
Maybe a clean up would help breathing/mpg on the 11 yr old hiace
Not sure I ever get THAT bored - but I will look to see how easy/hard it appears initially, as it sounds a very worthwhile task
Thanks again
Chris
- (#8986) Chris Turner, 7 Jun 03 5:22
Well I pulled the intake pipe leading to the manifold and utilised a dental mirror and torch
Not to bad - probably more like my lungs than a usa vw - an evenish coating of soot with some 4mm lumps - will have a closer look when I do the rocker cover gasket as someone has pulled the intake pipe before me and the gaskets there look like replacement would be useful
Manifold (3L)itself does not look easy to pull without removing alot of ancillaries and possibly the deisel pump - and even then looks awkward as little engine bay space
So alls well for the mo
Chris
- (#8987) chris turner, 7 Jun 03 8:41