V60 D5 mpg lower than normal

[dhr90]

For the past 2-3 weeks now my average mpg, and the instant readings on the dash have been much lower than when I got the car 9 weeks ago or so. I had been averaging 44-49mpg on my way to and from work, now I'm lucky to get more than 40, and usually only get 33mpg.
This is read from trip statistics under My Car.

I've also noticed a whistling noise from the engine that I'm sure wasn't there when I purchased the car, which is definitely getting worse, very noticeable with the windows down and accelerating, but also noticeable at certain constant speeds, 28mph and 39 mph are very clear.

Feels like it may be a little down on power too, but not being used to such torque yet I can't be sure.

I have a basic OBD II code reader which has found no codes. I'm sure it can't be the DPF given how long its been going on for, and that had a regen maybe 300 miles ago so I wouldn't expect it to have filled so quickly? Only had one regen that I noticed in the 2000 miles I've driven since owning it (have done a lot of motorway miles).

I'm also finding some journeys the range readout will drop by 20-30 miles for a mile or two driven, and other times I can drive the same 7 mile commute and the range will increase by 10-15miles.

The whistling makes me wonder about a boost leak? Is this something that would be resolved under Volvo Selekt?
Any other ideas?

[AndyJudge]

Pretty sure any of that sort of leak would be covered under Selekt agreement.

Best bet would to take it in.

If it's not covered you can always look for an indie to fix it but pretty sure it will be.

Good Luck & keep us posted

[craigv60]

Have a look under the bonnet in bright daylight, and feel along the big black rubber hoses that carry air under pressure from turbos to intercooler, and intercooler to inlet manifold. It helps if you pop off the plastic engine cover.

If you find oily, cruddy, mucky smears on them, especially around the joints where the hoses are clamped with jubilee clips, there's your leak.

Hoses can fray and split; but also, there are some 8 or 9 joints where the hoses mount onto a spigot, and these joints rely on a simple jubilee clip to retain boost pressure. Over time, the hose gets compressed under the clip and the clip will no longer be securing the joint properly - which can lead to boost leaks.

Using a screwdriver or a 7mm ring spanner / socket, you can get at & tighten many of the clips yourself. Usually, a full turn of the screw will clamp things down firmly so they won't need doing again. Only takes 10 minutes. It's worth wearing some rubber / latex gloves though, 'cos it's a bit of a knuckle-skinning job getting at some of the clips.

If you're REALLY keen, get the front wheels on ramps (or on a raised kerb or similar), drop the engine undertray, and get underneath. The first pipe which carries boost from the turbos to the intercooler inlet has two or three clips on it which WILL be a bit loose after 5 years.

[dhr90]

Originally Posted by craigv60

Have a look under the bonnet in bright daylight, and feel along the big black rubber hoses that carry air under pressure from turbos to intercooler, and intercooler to inlet manifold. It helps if you pop off the plastic engine cover.

If you find oily, cruddy, mucky smears on them, especially around the joints where the hoses are clamped with jubilee clips, there's your leak.

Hoses can fray and split; but also, there are some 8 or 9 joints where the hoses mount onto a spigot, and these joints rely on a simple jubilee clip to retain boost pressure. Over time, the hose gets compressed under the clip and the clip will no longer be securing the joint properly - which can lead to boost leaks.

Using a screwdriver or a 7mm ring spanner / socket, you can get at & tighten many of the clips yourself. Usually, a full turn of the screw will clamp things down firmly so they won't need doing again. Only takes 10 minutes. It's worth wearing some rubber / latex gloves though, 'cos it's a bit of a knuckle-skinning job getting at some of the clips.

If you're REALLY keen, get the front wheels on ramps (or on a raised kerb or similar), drop the engine undertray, and get underneath. The first pipe which carries boost from the turbos to the intercooler inlet has two or three clips on it which WILL be a bit loose after 5 years.

Found one such oily greasy smear around a joint near the top, how long a fix will it likely be to tighten it? Tried to hold some tissue paper next to this bit with the engine running in the hope of seeing a leak move it, alas that didn't happen. Still likely the cause though?
Couldn't see down far enough, even with a torch to see any of the other connections, not much space in engine bays these days!!

I also discovered what looks to be a missing bolt where one of those pipes has a bracket or support that stretches to the back of the engine, it has a hole through and there appears to be a thread in the metal underneath it. Looks like an M5 or M6 thread. Its positioned just next to where the grease mentioned above is coming from.

[craigv60]

Without seeing which hose it is exactly, it's hard to say. Any chance you could snap a pic of it? Is it a hard plastic hose or a rubber hose?

[dhr90]

Originally Posted by craigv60

Without seeing which hose it is exactly, it's hard to say. Any chance you could snap a pic of it? Is it a hard plastic hose or a rubber hose?

At the top, the big hose here, think its plastic rather than rubber from memory?



And this is the missing bolt location, shot from the other side of the pipe at the top of the engine. Seems to be the same flange from the first photo which goes to the right and behind that silver bolt.

[craigv60]

That looks like the plastic pipe that runs from the airbox to the turbo inlet ... it doesn't carry boost pressure so is unlikely to be the problem.

The oily crud has probably come from somewhere else. It is worth checking the hose clip is snug and tight, though. Get a 7mm spanner on it and gently tighten half a turn if you can.

[S60RDesign]

This might sound daft but without hearing your specific noise, it couldn't be a sticking brake caliper could it? That would probably cause a squeak and increased fuel consumption too

[dhr90]

Originally Posted by craigv60

That looks like the plastic pipe that runs from the airbox to the turbo inlet ... it doesn't carry boost pressure so is unlikely to be the problem.

The oily crud has probably come from somewhere else. It is worth checking the hose clip is snug and tight, though. Get a 7mm spanner on it and gently tighten half a turn if you can.

Gave it a little tighten half a turn, didn't seem to have any impact this morning, usual poor MPG. This evening I still got the whistling noise, but the car read an average of 57mpg, I was amazed!!

Originally Posted by S60RDesign

This might sound daft but without hearing your specific noise, it couldn't be a sticking brake caliper could it? That would probably cause a squeak and increased fuel consumption too

I don't believe so, its loud on hard acceleration and quiet on soft and goes when I stop accelerating and stay at a constant speed, its also the same volume at various constant speeds (30, 40, 50 mph). It was also there this evening when the mpg was far higher.

I've got the car booked in to be looked at on friday, hope a problem is found and solved quickly!

Couldn't be DPF regen related could it? I thought I could hear a boom noise lately at times, but to have been doing it for maybe 3 weeks and 200-300 miles would be odd? Have had a couple of 20-40 miles trips in that time which I would have thought would be enough for the majority of a regen? Also thought the D5 was pretty reliable in the DPF department, at least compared to others?

[craigv60]

Originally Posted by dhr90

Couldn't be DPF regen related could it? I thought I could hear a boom noise lately at times, but to have been doing it for maybe 3 weeks and 200-300 miles would be odd? Have had a couple of 20-40 miles trips in that time which I would have thought would be enough for the majority of a regen? Also thought the D5 was pretty reliable in the DPF department, at least compared to others?

A regen wouldn't cause the whistling, and wouldn't go on for THAT long ... my old 5-cylinder D3 163bhp would take about 15 minutes to do a full regen after prolonged town work.