1998 S70 GLT Lost Thermostat Bolt

ashyu · Post by **ashyu** » 17 Jan 2015, 08:54

I was replacing the thermostat on my 98 S70 and accidentally dropped one of the bolts.. it is the one on the upper right corner of the housing (the more difficult to reach one close to the fuel rail).

It just to the left of the housing straight down - I can't seem to see it anywhere - any suggestions as to how/where it might have gone and if there is any chance of getting it back without starting to take everything else apart?

Or at the very least, is this a standard screw that I could pick up from anywhere? My local Volvo doesn't have any right now..

Post by **xHeart** » 17 Jan 2015, 09:21

Take the other one to nearest hardware store and get two. Some suggest to use hex flange head for ease of use.

Few threads short is ok, not more.

Post by **jblackburn** » 17 Jan 2015, 10:35

+1 on the hex head bolts - the Torx ones usually become a PITA to get out the next time that you need to do a thermostat change.

Post by **cn90** » 17 Jan 2015, 10:53

1+,

M7 bolts...

https://www.matthewsvolvosite.com/forums ... =1&t=34806

Post by **rspi** » 17 Jan 2015, 11:31

I actually use intake manifold bolts now.

Post by **FLXC90** » 17 Jan 2015, 12:26

Try fishing for it with a retrieval magnet. Make sure it is not in the area of the belts if it could have gotten in there. Use a flashlight and a hand mirror to peek in wherever you can.

ashyu · Post by **ashyu** » 17 Jan 2015, 12:49

Thanks all - man it seemed nearly impossible to find M7 bolts!

I went to my local Home Depot and they said they only carried the even numbers like M6 and M8, but no M7... a local auto parts store didn't carry any either (only M5, M6 and M8...). I ended up finding a store specializing in nuts and bolts in a neighbouring city that had a few M7 bolts and luckily I managed to get a taxi down to them just before they closed.

I had trouble getting my socket and extension in between the fuel line that is over top the upper right corner of the thermostat housing, so I reused the one torx screw I still had for now.

Put everything back in and took the car for a test drive, and things seem ok (temperature gauge gets up to 3 o'clock and cabin temperature was nice and warm).

I looked more for the bolt but couldn't see anything at all. It fell to the right of the thermostat - most of the belts look like they're to the left?

villagepc · Post by **villagepc** » 17 Jan 2015, 14:13

yes - the serp belt is at the front (left side) of the motor as you stand looking into the engine bay. The bolt monster got one of mine too - and it ate one of my T40 torx wrench thingies too. I still haven't seen hide nor hair of 'em. And what a mystery that's proven to be. Just poof- gone.

The only thing that's going to be under there will be the PCV system (which is a closed system) and maybe the harness for the knock sensors.... I can't think of anything right off the top of my head that would be a cause for a huge alarm to go chasing that bolt down.

Just on a cautionary note - I'm dealing with the 3 o'clock temp gauge thing too - have you replaced or tested your ECT to verify its functional ?

Also - you can depressurize the fuel rail and disconnect the fuel line right there. Won't hurt anything - just be sure and catch the spilled gas with a towel / rag..etc. I think its a 17? Ya might need a 17 and a 14 at the banjo... either way - that made the job easier for me.

ashyu · Post by **ashyu** » 17 Jan 2015, 14:21

I didn't replace the ECT sensor yet - they are quite a bit more pricey when compared to the thermostat, so I wanted to just try the thermostat replacement first to see how that goes.

I had found that while driving at constant speeds, the temperature gauge would drop. In severe start-stop traffic, it could get up to 3 o'clock, but only to drop back down against once I picked up speed.

The weather warmed up a bit where I am this week (which is why I decided to do the replacement this weekend), I'll have to see how the temperature gauge behaves on my commutes to work next week.

Post by **misha** » 17 Jan 2015, 14:50

ashyu wrote:...I had found that while driving at constant speeds, the temperature gauge would drop. In severe start-stop traffic, it could get up to 3 o'clock, but only to drop back down against once I picked up speed...

Those are the symptoms of stuck open or lower degree thermostat-unapropriate one.

Thermostat for non turbo must be in 87-92 degree range.