Knocking noise when lifting off

Technical questions and answers about the Mazda Bongo

Moderators: Doone, westonwarrior

Post Reply
Merlot man
Bongolier
Posts: 386
Joined: Mon Aug 15, 2016 4:06 pm
Location: Co Clare, Ireland

Knocking noise when lifting off

Post by Merlot man » Sun Nov 17, 2019 6:09 pm

Hello all
I haven't been in for a while so sorry about that .
I have a 95 4wd bongo and when driving I get a bad knocking noise when lifting off the throttle of going down hill , it's Been getting worse this last while , I've checked and there's nothing loose underneath , exhaust , suspension etc
It seems to be coming from the middle of the bus and I'm now thinking it might be the transfer box ?
Has anyone else come across this and how did you solve it ?
We have no bongo specialist near us here in Ireland so that's not an option I'm afraid
Thanks in advance
Brian
User avatar
g8dhe
Supreme Being
Posts: 10179
Joined: Sun Apr 13, 2008 10:06 pm
Location: Worthing, West Sussex.
Contact:

Re: Knocking noise when lifting off

Post by g8dhe » Sun Nov 17, 2019 9:04 pm

Could be the CV joints on the prop shaft perhaps ?
Geoff
2001 Aero V6, AFT, full side conversion.
Image Spherical Visions
Ian
Supreme Being
Posts: 5885
Joined: Wed Jun 09, 2004 2:47 pm
Location: Bongo Mission Control

Re: Knocking noise when lifting off

Post by Ian » Mon Nov 18, 2019 10:25 am

Brian, could it be the front diff? Here's an extract from the "Differential" fact sheet in the members area:

We have had a couple of instances where members have reported completely “mashed” differentials that have had to be replaced. In both cases it happened on four wheel drive Bongos, and both were caused by the same problem: incorrect tyre sizes! Take a look at this extract from the Bongo Clinic:

Q: I have a 4WD Bongo. Recently my front differential overheated and was totally destroyed. I replaced it but this also over heated. I have been told that it may be due to incorrect tyre sizes, but I have checked an mine are 195/70/R15 on the front and 215/70/R15 on the rear. (Craig from Falkirk)
A: They are not the correct tyre sizes. The correct rear tyres should be 215/65/R15. The middle number is the tyre profile. Your’s is 70 and should be 65. This means your rear tyres are standing too tall, which, over time, knackered your diff. The fact that a second diff experienced the same problems means you may have also damaged your transfer box and viscous coupling. This will need to be checked thoroughly.
668. The Neighbour of The Beast.
Merlot man
Bongolier
Posts: 386
Joined: Mon Aug 15, 2016 4:06 pm
Location: Co Clare, Ireland

Re: Knocking noise when lifting off

Post by Merlot man » Mon Nov 18, 2019 9:41 pm

Thanks for the replies lads .
I've been under the bus tonight to see if I can see anything and to be honest everything looks good , damn ! :evil:
I put a bar into all the joints and nothing seemed to be badly worn out . To be honest I was hoping to find the gearbox mount worn out but no such luck !
I don't have a lift and I'd really need one to get a good look at everything so I'm going to try and get a garage locally if I can to have a look over her aaaahhhhhhhhhhh
Ian , sense I've had the bus she has had the correct sized tyres front and rear but I can't say before that .
The noise is coming from the middle of the bus so front diff , I don't know ?
As always thanks for the replies and all susgestions will be looked at , this has me stumped :-#
Brian
Post Reply

Return to “Techie Stuff”