Viking lawnmower

[GregMc64]

Hi all.
Fairly new to gardening and basically clueless in all but the most basic of tasks!
Just joined in the hope that someone can give some advice on my viking lawnmower which seems to be losing drive. Thinking back this has been going on for some time with a reduction in the speed of the drive but the last couple of times I've used it the mower has intermittently been unable to drive itself.
Any suggestions gratefully received
Thanks
Greg

[Mick]

Hi Greg, and welcome to TGMForum.

Do you know what model Viking you have, just so we know what machine we're dealing with?

[GregMc64]

Hi Mick.
Thanks for the welcome to the forum.
Its an MB650.3.
Suspect it's the belt tension causing the issue but can't see how to get at it. There are two bolts underneath but these seem to be holding the whole thing together!

[Mick]

Thanks, does it have a letter after those numbers, such as a T or a V? 

One is a fixed speed and one a Variable speed as far as I can remember.  I've only worked on a few of these before they changed to Orange and rebranded to STIHL.

[GregMc64]

Hi. Sorry for the delay. Been away for a week. It doesn't have a letter but I'd definitely variable speed however varying the speed control has made less and less difference over time

[Mick]

I'm wondering if your engine pulley is stating to hang up.  I've seen a few of these where the aluminium part that goes through the pulley has stated to split and that stops the front pulley from closing via its spring.  It's usually the front pulley or a worn belt which affects the variable drive, and drive as a whole.

I would start by looking at the pulley on the engine first and see if it's getting stuck.  The whole pulley assembly pushes onto the top of the blade adaptor and looks like this, https://www.lsengineers.co.uk/v-belt-pulley-mb650-lawn-mower-63607002501.html

[GregMc64]

Hmmm.....
Sounds like a big job, mainly due to my lack of technical expertise!

[AdviceFromGarage]

Hi Greg. From what you write, it could be a damaged (worn) V-belt, a damaged gearbox or something else. But you might just need to adjust the drive cable a little with the rotary knob. On my mower, the knob is under the green plastic cover on the bottom of the left handle. You might not have even noticed it was there before. You can see it in the video. If it's a belt, I can also help you, since I recently changed the V-belt on my Viking MB 650 T. I recorded the whole thing on video and posted it on my YouTube channel. I think it could help you a lot, at least you'll see what the V-belt and pulleys look like. Changing a belt is not as difficult as you might think. I've never done it before and I managed it. It's very easy on these mowers if you know what to do. And after watching the video you'll be able to do it. Although I have a single-speed gearbox (marked in the name of the mower "T") and you probably have a VARIO drive (marked in the name of the mower "V"). Even removing the gearbox and axle is very easy on this mower, if you want to do it. I have made several videos on my channel for both VIKING mowers and some others. Good luck. S.

[Mick]

Thanks AFG, I'm sure someone will find this very helpful, although (just noting) this is for the none variable speed version of this machine.

GregMc64 hasn't been back since so I've no idea if he got it fixed.