TURBO NOISE/FUEL CONSUMPTION

[gumby6371]

After doing a basic service (oil, filters etc..) I've noticed a slight whine from the turbo when it kicks in at about 2 - 2,500 revs, not had the car very long and it's my first turbo so i was wondering if this is normal ?
Started to hear the turbo a few days after doing the service, the oil did look a lot like treacle when it came out! To my untrained ear I would say the noise is the turbo spinning up.
To be honest it is picking up a lot better and there seems to be more power so I'm assuming all is good but just wanted to check.

Another quick question is what MPG should I be getting from a 97 1.9td GLX ? the trip computer doesn't give me an MPG reading (apparantly it doesn't work on a diesel ?) but I've guesstimated I'm getting about 30 out of her, but that is all stop/start town driving.

[Welly]

Just sounds like the turbo is more able to spin up to speed in the nice new oil so I shouldn't worry - in fact the turbo's rarely give any trouble and the engine's allways seem to be able to recover from any previous neglect (oil wise).

MPG wise i'm not sure but I'd say 30-35 in town and 40-45 on a run (ish).

[mandelbug]

It could well be the turbo spooling up, especially if it's a whistling type noise.

As for MPG on my last tank with a lot of stop starting (although it did do a run from Manchester to London via Leamington Spa) I got 41mpg. Normally with runs I am getting 45+ out of my 1.9 TD LX

[easthams1958]

Dont know much about Turbo's but since when would they "spin better in nice new oil". I was under the impression that they acted like a super hair dryer and oil in them would be the sign of a major problem???

[Welly]

I meant that the bearings, which operate on a coat of oil, will be 'free' if the previous oil/bearings were nasty and gunked up - I was exagerating the point slightly but it's not unreasonable for a turbo to spin more freely after an oil change.

Oil IN the turbo/impellor housing is bad news as it will produce smoke and potentially wreck the engine.

[easthams1958]

Does that mean then that the turbo lubrication is fed from the engine oil?? I have just bought a 2002 2 litre 406 110 and am finding that the turbo kicks in and power is there but disssipates very quickly. Also do you know if the Turbo will remain working at say 90mph plus?? I am yet to do an oil change so very interested in your reply??

[mandelbug]

Turbo oil feed is usually from the block of the engine and they share the same oil.

The turbo doesn't continually operate and when cruising may well stop boosting. Turbo's on diesels work slightly differently to turbo's on a petrol. They tend to be smaller and "kick in" lower in the rev range to help build revs and speed up. Turbos on petrol cars tend to be there to add power to the top end of the rev range

[Welly]

The turbo on the HDi (despite being very whistley) boosts very early on between 1750 and 2900 revs whereas the older 2.1td behaved almost like a petrol and was quite top-endy but this harms fuel consumption and emissions

The turbo on a diesel basically comes in and out according to throttle position (fuelling) and is controlled electronically mostly. At high engine revs (above 4000) then a diesel's turbo is out of it's operating range and having little effect even though it'll be spinning away like mad.

The reason we started talking about oil and the turbo was that on some cars (VW TDi's spring to mind) the oil feed to the turbo is quite a long run of piping and can block up if the car hasn't been serviced properly leading to turbo failure. The oil is 'tapped in' to one of the engine blocks' oil galleries to supply the turbo bearings and then drains by gravity to a lower tapping on or above the sump pan. The HDi does not suffer oil blocking problems usually as the supply pipe is short and the turbo does not run hot (it doesn't even have water cooling). The older petrol turbo does have problems though because it gets much hotter.

[easthams1958]

So would you the say at 80mph in 5th if I floored it there would be very little effect gained from the turbo??? or should there be??? It seems at that speed I justs have to wait a long time when pedal to metal for any increase to be apparent. Also are there any obvious/easy things beside a full service I could do to improve things or is that just the way the car is?

[Welly]

At 80mph in 5th you should be doing around 2400 revs so well within the boost range in fact the 80 to 95 acceleration is probably the most impressive feature of the HDi so it sounds like yours aint playing ball for some reason.

You could look for signs of splits in the vacuum hoses to the bulkhead solenoids or signs of oil around the intercooler and turbo hose connections (may be a boost leak somewhere) other than that it's down to reading for fault codes and looking at the live fuel pressure to see if anything's a miss?

[easthams1958]

Whereabouts is the intercooler??? If I look down into the engine bay there is something that looks like a radiator to the right of the actual radiator. This has thick oil/sludeg deposits sat at the bottom on a ledge as you look down but that may have filcked off from somewhere lese in the engine???

[Welly]

Yup, it's the small radiator to the right (about the size of a shoe box).

Any black oil deposits round there spell a leak either in the large bottom hose or the intercooler itself - try and peak at it through the front lower grill with a torch as well.

The underside of the bottom hose is favourite and is unfortunately damaged indirectly by the engine rocking about too much thanks to the rear engine mount (got the T-shirt) feel around underneath the hose and if it's all squidgy and feels like you could poke your finger through it then you need a new one. To be fair though you can normally hear a boost leak unless it's a massive hole in which case it would be quiet.

Also give the engine a 'blip' whilst it's running by reahing for the throttle sensor (behind the battery with the accelerator cable attached to it) if the engine lurches forward by more than 25mm when you blip then the engine mount is worn! - don't leave it too long if it is because it can rip through the exhaust flexi down pipe too (T-shirt).

[Welly]

Bugger, just realised we've knicked this guys thread haven't we?

Sorry everyone

[easthams1958]

Not too worry I am sure the originator has learned a lot as have I. Thanks for all that I will no doubt get some spanner rash over the weekend!! Any idea on the cost of pipework should it need replacing?? Also I would assume with what you said in mind that if my air filter is clogged then there would be a shortage of air at high speeds as that is when it would need the most so that could also be the cause. My previous car mondeo tddi 2001 ended up be sold for spares as Iost compression in one pot and it was either a sticky valve (which they said at the garage would be in the region of £500 to replace) or bent rod shot rings etc (which would have been anywhere between £1000 and £1500) I sold it to a mate and he put a 70k donkey in it and when they removed the old engine they found a 6 inch split in one of the turbo pipes (this probabaly caused the death of it). I had it in 3 garages prior to this happeneing due to the reduction in power and not one of them spotted it which was probably down to the inaccesibility of the pipe so you couldnt see the split. Hence my mistrust of Turbo's. Thanks for all the info and now hoping for a good result after the weekend.

[Welly]

The bottom intercooler hose is about £57.00 I think.

If you have the bottom undertray off (most peoples trays just fly off on their own so you may not have one) then you can see the turbo piping right back to the turbo as it passes under the sump (in plastic). It's worth going over all of it and tightening any hose clips but also look carefully at the small tubing going to/from the vacuum solenoids on the bulkhead as they control EGR and Turbo functions and could be at fualt (you can swap them about for trial and error purposes).

A clogged air filter won't be helping matters but it's worth noting that a diesel engine 'inhales' the same amount of air right through the rev range (excluding the turbo boost) as there is no throttle butterfly like a petrol; in any case it's worth fitting a new one (from the dealer for what they cost).

Pardon me for asking but your mate put a 70K Donkey in your Mondeo? now I am confused