Underside/tunnel heatshields

[foggyjames]

Hi team!

I've been conscious of a rattling from under the car which has been getting steadily worse over the past 2-3 weeks. I finally got chance to have a look in a gap in the rain(!) yesterday, and discovered that one of the alloy heatshields which runs along the transmission / exhaust tunnel has sheared at one of the mounting points.

They were both removed and reinstalled relatively recently (within 15k miles). Any chance I did something wrong whilst reinstalling them? If so, what?!

Any one got any ideas?

cheers

James

[Ian21401]

My daughter has a 2011 XC70 and, as yet, no heat shield problem bit I’m expecting them to fall off. I have a 1992 940, it’s the first car that I have owned which has/had heat shields. None of my previous non Volvo cars had them. The heat shields on my 940 have fallen off frequently. Usually caused by the alloy of the heat shield corroding away around the fixing. I was able to remedy some of these by using some large washers but sometimes the actual fixings through the floor pan had corroded away. I gave up eventually. If they were not easily re-secured I just left them off.

[Tatsfield]

Do the heat shields actually contribute anything worth the bother of replacing them?

[Clan]

Originally Posted by Tatsfield

Do the heat shields actually contribute anything worth the bother of replacing them?

volvo put them there for a reason of course , they get up to 600C when regenerating !

[Ian21401]

Well I hope that the shields and fixings on the XC70 are better designed/engineered than the ones meant to be on my 940 as they seemed to have been stuck on as an afterthought. Small steel screws through the floor pan and through a thin sheet of aluminium. Electrolytic corrosion. Very non Volvo.

[Clan]

Originally Posted by Ian21401

Well I hope that the shields and fixings on the XC70 are better designed/engineered than the ones meant to be on my 940 as they seemed to have been stuck on as an afterthought. Small steel screws through the floor pan and through a thin sheet of aluminium. Electrolytic corrosion. Very non Volvo.

Very secure no problem at all .
I remember a recall for the 940 front pipe heat shield cracking and dropping down in the 1990's..

[GrahamHR]

Originally Posted by Clan

Very secure no problem at all .
I remember a recall for the 940 front pipe heat shield cracking and dropping down in the 1990's..

A common problem on all cars in the UK where such heatshields are fitted; aluminium heat shield, steel studs and nuts, salt, ===> corrosion of the aluminium. Salt is not used on the roads in Sweden in the winter.

I repaired the mounting holes of the heatshields on my Mondeo ST220 using adhesive backed aluminium on each side of the heatshield, with insulating tape under the nuts; they never corroded again.

[foggyjames]

Thanks for your replies. These are rather less solid than the old 940 ones, so if you don't like those...!

No corrosion here (unlike the various Ford-spec suspension arms...!), just sheared off. I guess I must have installed it slightly in tension, but it's a bit odd...!

cheers

James

[Clan]

Originally Posted by GrahamHR

A common problem on all cars in the UK where such heatshields are fitted; aluminium heat shield, steel studs and nuts, salt, ===> corrosion of the aluminium. Salt is not used on the roads in Sweden in the winter.

I repaired the mounting holes of the heatshields on my Mondeo ST220 using adhesive backed aluminium on each side of the heatshield, with insulating tape under the nuts; they never corroded again.

volvo have been using plastic nuts for the last 20+ years no problems at all , in fact the shield material may well be stainless steel .

[Ian21401]

Well the fixings on my 27 years old 940 were/are definitely steel and the shields appear to be thin sheets of aluminium.
Would stainless steel corrode away around the fixings?