remove variable geometry on trubo

rodiram · Post by **rodiram** » 07 Apr 2020, 08:53

Hi all,
I am replacing a CHRA on a turbo (volvo part number 31219697, V70 D5244T5).
The turbo is open, I now need to remove the variable geometry. The geometry is attached to the CHRA with 5 small torx screws. Even with WD40 I was able to remove only 2 of them, the 3 others are stuck and I am starting to damage their heads. Is that a common issue ?
Thank !!

Post by **SuperHerman** » 07 Apr 2020, 09:19

I don't recall 5 small torx screws. I pulled up some pictures of the part number you list and cannot find five torx screws

Can you post a picture?

rodiram · Post by **rodiram** » 07 Apr 2020, 11:00

Thanks, here:

: Screen Shot 2020-04-07 at 18.58.33.png (751.49 KiB) Viewed 1003 times

:

rodiram · Post by **rodiram** » 07 Apr 2020, 11:07

CHRA alone looks something like that:

: Screen Shot 2020-04-07 at 19.05.42.png (871.14 KiB) Viewed 1001 times

Post by **volvolugnut** » 07 Apr 2020, 11:31

One of these manual hammer impact tools work well for stuck fasteners. If it does not come with the bit you need, used adapters from sockets to get to the tip you need. Various brands and prices are available. Harbor Freight works ok.

volvolugnut

Post by **SuperHerman** » 07 Apr 2020, 15:27

Ah - the devils in the details. Missed you have a diesel engine and have now learned the diesels use a Garrett turbo rather than a Mitsubishi like the petrol versions.

How did the one screw you remove look like? Any signs of corrosion?

Here are the tricks to removal, basically in escalating order. First though secure the housing in a vice or other manner so that it is not going to move and you can get which ever bit you use going straight. Tap any bit so it is firmly and straight in place. Give it a good rap - sometimes helps break any bond. If you have a impact screw driver, liked shown above, try that.

1) Try a quality grade bit,
2) Try turning bit counterclock wise ever so little to break any bond,
3) If the head is too messed up, try going up one size, maybe try an allen (you need to experiment). The head is messed up so you cannot ruin what is ruined.
4) You can try this before #1 or at any point, drill a very small hole straight into the screw. Dead straight - use the bolt you removed to get the maximum depth. Many times this will be all you need.
5) As the bolt head is recessed, it would be tough to cut a grove for a standard screw driver - give it a go. Otherwise try enlarging the screw hole so you can use an easy out.
6) Use the bolt you removed to figure out the maximum width and depth (of torx head portion) you need to drill out. What you are shooting for is just leaving the stump. Once the head is off - you should be able to pull the part off and use a vice grip to take off the remaining stud.

That is the approach I would use. Each step is an escalation in destruction, but since the torx bolt is messed up they need to be replaced anyways. The key is to try and do as little work as possible and to not damage anything but the stuck torx bolt.

Good luck

Post by **chrism** » 07 Apr 2020, 19:43

Sometimes you can take a drift that is small enough in diameter to loosely fit down into the torx hole. Smack the drift a few good blows with a hammer. It will slightly force the bolt shank downward and relax some of the load on the threads, allowing you to more easily unscrew the bolt.

rodiram · Post by **rodiram** » 08 Apr 2020, 14:08

Thank you all. Sounds like good suggestions. I will probably wait till the lockdown is over here to do that so I can get proper tools. Do you think I can also try with a torch ? The steel looks thick enough not to damage the turbines.

Post by **SuperHerman** » 08 Apr 2020, 20:50

It is a turbo - it gets hot. My concern is if there are different metals - you may warp or crack something. Without knowing what the various materials are made of - I don't know what heat is safe other than anything below normal turbo temperature would be okay.

I would just find a small drill bit that fits into the hole without hitting the torx grip points and drill straight down. It should also be smaller than the threaded bolt portion. The heat and vibration usually is enough to get the bolt out. Just secure the turbo well and drill straight down. I am confident it will work. Drilling a hole through messed up bolts has always worked for me. Use oil so the bits don't overheat. Let the drill and bit do the work - not too much pressure. Even better, if you have the correct size reverse drill bit bolts usually come out on their own.

rodiram · Post by **rodiram** » 09 Apr 2020, 05:39

yes that makes sense, I just have bad experiences when drilling hard metals (like this screw seems to be made of), but with proper oil, a stand and good quality drills there is no reason it won't work. Thank's again for the suggestions.