D5 Intercooler - Possible solution?

[JimmyBurnWorld]

Finally got round to getting my V70 D5 into a garage long enough to go through the warranty process for getting my intercooler replaced.

Just thought I'd do a quick (or not) write up, with some pictures, and also propose a possible solution.

Symptoms:

Fuel economy - When I got the car it was doing (indicated) high 40's, averaging 46-48mpg. If I was light on the go-pedal, I could average 50 no problems. This had dropped steadily over the last few months to high 30's (averaging about 38mpg).

Hesitation - Random hesitation when booting it, or even when accelerating steadily.

Limp Mode - Had the car go into Limp Mode with fault code 'Boost Control Fault'. Only happened once, about a month ago.

Black Smoke - Increasingly more and more black smoke under acceleration.

Diagnosis:

Look through lower grille, heavy oil contamination on lower part of intercooler.

Put brother-in-law in car, got him to rev it while i held my hand infront and I could feel the air rushing out of it. Obviously porous.

So, booked it in and got it replaced under warranty (lucky). Invoice was £344 all in, for a Nissen intercooler, coolant replacement and labour.

Pictures:

Got the old intercooler back from the mechanic. As you can see, the lower bars have bent under boost pressure.

http://i564.photobucket.com/albums/ss81/jimmyburnworld/Intercooler/IMG_2248.jpg

In total I found 12 of the following holes. This is before I can be bothered to clean the oil off and inspect further. The holes are on both sides of the Intercooler

http://i564.photobucket.com/albums/ss81/jimmyburnworld/Intercooler/IMG_2256.jpg

http://i564.photobucket.com/albums/ss81/jimmyburnworld/Intercooler/IMG_2251.jpg

Now, my opinion.

The intercooler construction consists of a series of 'bars' running horizontally between the two end caps. Welded in the gap between these bars are a series of 'fins'. These are attached to the bar either side of the gap.

As the intercooler distorts, ie the bending observed, the gap between the bars wants to grow. All that is stopping this from happening is the fins that are welded to the bars. Something has to give, and as such the bars tear where the fins attach to them.

The D5's intercooler is wide and thin, therefore there is a long unsupported distance between the end caps.

I believe, if a 'strap' or 'tie-bar' was added to the middle of the intercooler (top to bottom) to tie the middle section of the intercooler together, this would prevent the bowing of the bars. If this was prevented, the fins wouldn't tear out. Result - No more porous intercoolers.

Any thoughts?

Sorry for the long windedness. I will average my mpg over the next few tankfulls and post back. The car certainly feels better at the top end, now that 99% of the air the turbo's shifting, isn't being blown out the front of the car!

[p fandango]

the idea of strapping the intercooler could possibly work, its an old trick that used to be done on Renault 5 turbo's to hold them together. I got a new intercooler for £100 (Nissens) so just replace it when it goes, old one lasted 140k miles so not exactly going to be a weekly thing

[wegal]

the idea of strapping the intercooler could possibly work, its an old trick that used to be done on Renault 5 turbo's to hold them together.

yeah but you used to strap the WHOLE R5 together not just the intercooler :-)

[p fandango]

yeah but you used to strap the WHOLE R5 together not just the intercooler :-)
i didn't think there was any bodywork strong enough to hold a cable tie lol

[jardon]

Some homework for when the new one goes:

http://forums.t5d5.org/topic/15903-radtec-ic-gearbox-oil-cooler/page__p__185169__hl__intercooler__fromsearch__1#en try185169

or

http://forums.t5d5.org/topic/13471-another-d5-fmic-standard-front-end-part-1/

http://forums.t5d5.org/topic/13472-another-d5-fmic-standard-front-end-part-2/

or

http://forums.t5d5.org/topic/11397-fmic-on-a-163-d5/page__p__129214__hl__%2Bstation+%2Bmotorsport__fro msearch__1#entry129214

But yes you could try bracing it - the way they bulge and split is scandalous really. Is the car remapped?

[JimmyBurnWorld]

Car is standard. I had to have the Nissen oe quality replacement as it was through the warranty. I had looked into a 'Williams D5' route as I'm very impressed with Tim's work, but untill the warranty expires in October, I need to keep it standard.

I'm shocked at the power and economy that has suddenly returned. Car pulls strongly all the way through the rev range, it's lost the temporary lack of power straight off a cold start, and indicated consumption has gone from approx 38mpg to 47. And thats with me exploring the new found power.

[JimmyBurnWorld]

Well, all seems well since the new intercooler, however I have a question about the new noises the engine is making.

Just been out for a few runs for work and I've had my windows down. I've noticed the sound from the turbo is very noticible now (the high pitched whistle, not the sound of air escaping under pressure) - Is this normal for a D5?

Also it has a new 'chirp' when under load which sounds like a dump valve activating. I'm guessing this is exactly what it is, but again is this normal?

Does the engine management have to re-learn the new operating conditions of the intake system now it isn't full of holes? If so how long does it take to adapt?