Holts Gun Gum for blowing backbox ?

Sheraton · 3rd August 2016, 07:23

How'do folks

My car has been running well since her head gasket repair

However - mot is due in 4 weeks ....... will she pass

I have a new cat to be fitted before then as the one on the car is goosed.
but i've noticed a couple of wee holes in the backbox, it's the original exhaust and the whole of the outer skin is gone

has anyone any experience of Holts Gun Gum ? and would a repair such as this be likely to pass mot inspection ? i assume, as long as it doesn't leak exhaust gases it would be fine ?

this will be the first time i take a car for an mot

Paul........

john2443 · 3rd August 2016, 07:32

Gun Gum might work and hold on long enough for the MOT, it might work for a year but might fall out in 10 mins!

Monty Hotspur · 3rd August 2016, 08:50

Gun Gum will struggle to stay in place - the gas pressure will likely blow it straight out.

If you use it and cover with an exhaust bandage then you will have a better chance of it sealing up and staying in place until at least after the MoT.

However, if you are going to all the trouble of replacing the cat then the backbox is an easy 10 minute job.

SD1too · 3rd August 2016, 08:56

Quote:

Originally Posted by Sheraton

... it's the original exhaust and the whole of the outer skin is gone

Don't worry; it will last for ages in that condition. Mine did.

Quote:

i assume, as long as it doesn't leak exhaust gases it would be fine ?

That's correct Paul.

Simon

Lord of Hog · 3rd August 2016, 09:03

A combination of gun gum, aluminium foil and exhaust bandage will probably sort it. Make sure you just let the engine tick over, or take it for a very gentle drive, for the first 20 minutes or so after you've applied it. Otherwise it will blow out before it's set. You could replace the rear box. As others have said, it's not a massive job (just make sure you give those hangers a good lubrication).

What does seem to be a recurring theme with others though is that, unless you spend the dough on an original box, there does seem to be an issue with resonance resulting in an unwelcome booming noise usually between 1500 and 2200 revs. This may simply be because cheaper boxes aren't made to the same standard. My thoughts are that it's a combination of that and the fact that the boot floor and bumper create a little echo chamber on four sides of the rear box which amplifies the sound. I'm going to have a go with various sorts of muffling and see if it makes a difference.

So in short, how much do you want to pay and what (beyond getting through the MOT) is your preferred result?

Sheraton · 3rd August 2016, 09:09

cheers folks

i'd ideally like to change the backbox (it will be replaced asap) however i don't have funds to do this before the mot

so off to halfords for Gun Gum it is

we'll see how it goes.......i figure if i do it now, i'll have a couple of weeks to see if it does the job and holds up - if not, i'll have a bit of time to see what i can do r.e replacement backbox.

Paul........

Sheraton · 3rd August 2016, 09:26

Quote:

Originally Posted by Lord of Hog

What does seem to be a recurring theme with others though is that, unless you spend the dough on an original box, there does seem to be an issue with resonance resulting in an unwelcome booming noise usually between 1500 and 2200 revs. This may simply be because cheaper boxes aren't made to the same standard. My thoughts are that it's a combination of that and the fact that the boot floor and bumper create a little echo chamber on four sides of the rear box which amplifies the sound. I'm going to have a go with various sorts of muffling and see if it makes a difference.

So in short, how much do you want to pay and what (beyond getting through the MOT) is your preferred result?

I've read a few posts relating to this - i'd ideally like my car to be quiet and refined like a Rover should

at the minute i don't have much option, i have a replacement cat already and just about enough cash to have this fitted (the cat on the car is goosed and unlikely to pass emissions) the backbox has a slight blow, and the holed areas i can see are pretty small - so if she can get past the mot for now i'll be happy - i'll possibly try and get the quietest stainless catback system made up, as it seems (from others experience) almost impossible to match the original set-up for quietness.

Paul....

jonathan63 · 3rd August 2016, 10:00

Quote:

Originally Posted by Sheraton

I've read a few posts relating to this - i'd ideally like my car to be quiet and refined like a Rover should

at the minute i don't have much option, i have a replacement cat already and just about enough cash to have this fitted (the cat on the car is goosed and unlikely to pass emissions) the backbox has a slight blow, and the holed areas i can see are pretty small - so if she can get past the mot for now i'll be happy - i'll possibly try and get the quietest stainless catback system made up, as it seems (from others experience) almost impossible to match the original set-up for quietness.

Paul....

I'm no expert on exhaust systems but from personal experience I would never have another "stainless" steel exhaust. I had one fitted to a Volvo some years ago and it was much noisier than the mild steel system it replaced. The reason I was given, from a few sources, was that stainless steel is harder and resonates higher than mild steel, and as a result gives a sharper, crisper and louder exhaust note. Not what I wanted on a Volvo and definitely not what I want on my Rover. Good luck with it.

Re Gun Gum: perfect for what you need. Clean up the repair area, keep moist with a wet cloth, follow the instructions and BE QUICK after you mix the 2 parts. It works easily for a while and then....................goes off in a matter of seconds in your hands.

Sheraton · 3rd August 2016, 11:02

Quote:

Originally Posted by jonathan63

I'm no expert on exhaust systems but from personal experience I would never have another "stainless" steel exhaust. I had one fitted to a Volvo some years ago and it was much noisier than the mild steel system it replaced. The reason I was given, from a few sources, was that stainless steel is harder and resonates higher than mild steel, and as a result gives a sharper, crisper and louder exhaust note. Not what I wanted on a Volvo and definitely not what I want on my Rover. Good luck with it.

Re Gun Gum: perfect for what you need. Clean up the repair area, keep moist with a wet cloth, follow the instructions and BE QUICK after you mix the 2 parts. It works easily for a while and then....................goes off in a matter of seconds in your hands.

this is what had put me off going stainless initially - i don't want the "look at me" noise the boy racers like - however, from what i've read of others experience - replacing a blowing (original) backbox and leaving with a car as loud or louder than before

i'd rather have the performance and durability gains from a stainless system with the extra noise

does the Gun Gum Paste require a separate hardener ? i picked up a tin of the paste - haven't opened the tin yet to see if it's a 2 part mix, i'd assumed it was premixed ready to go as no mention of a mix on the tin and i never seen a separate hardener to buy

Paul........

jonathan63 · 3rd August 2016, 11:41

Quote:

Originally Posted by Sheraton

this is what had put me off going stainless initially - i don't want the "look at me" noise the boy racers like - however, from what i've read of others experience - replacing a blowing (original) backbox and leaving with a car as loud or louder than before

i'd rather have the performance and durability gains from a stainless system with the extra noise

does the Gun Gum Paste require a separate hardener ? i picked up a tin of the paste - haven't opened the tin yet to see if it's a 2 part mix, i'd assumed it was premixed ready to go as no mention of a mix on the tin and i never seen a separate hardener to buy

Paul........

My mistake (a few years since I used both products). Gun Gum is a paste you use straight from the tin, gives you a good working time and is good for what you need.
The stuff I kept my Lexus LS400 exhaust going on was http://www.4yourhomeuk.com/quiksteel...cRPxoCgwXw_wcB
It comes in a plastic tube about 3 1/2" long containing 2 parts: 1 grey 1 black. You cut off an equal amount form each part and mix the 2 together in your hand. Hard work at first, then it gets easy and you think "this is ok, I'll take my time". Then, suddenly, it sets hard in seconds. And it sets as hard as steel. I used it to rebuild the manifold to exhaust pipe flanges that had all but rotted away. It is amazing stuff.

3rd August 2016, 07:23	#1
Sheraton Posted a thing or two Rover 75 1.8t Join Date: Oct 2015 Location: Edinburgh Posts: 1,377 Thanks: 384 Thanked 409 Times in 267 Posts	Holts Gun Gum for blowing backbox ? How'do folks My car has been running well since her head gasket repair However - mot is due in 4 weeks ....... will she pass I have a new cat to be fitted before then as the one on the car is goosed. but i've noticed a couple of wee holes in the backbox, it's the original exhaust and the whole of the outer skin is gone has anyone any experience of Holts Gun Gum ? and would a repair such as this be likely to pass mot inspection ? i assume, as long as it doesn't leak exhaust gases it would be fine ? this will be the first time i take a car for an mot Paul........

3rd August 2016, 09:03	#5
Lord of Hog Gets stuck in Rover 75 2.5 V6 in Wedgwood Blue Join Date: Dec 2015 Location: Felbridge, East Grinstead Posts: 982 Thanks: 250 Thanked 294 Times in 206 Posts	A combination of gun gum, aluminium foil and exhaust bandage will probably sort it. Make sure you just let the engine tick over, or take it for a very gentle drive, for the first 20 minutes or so after you've applied it. Otherwise it will blow out before it's set. You could replace the rear box. As others have said, it's not a massive job (just make sure you give those hangers a good lubrication). What does seem to be a recurring theme with others though is that, unless you spend the dough on an original box, there does seem to be an issue with resonance resulting in an unwelcome booming noise usually between 1500 and 2200 revs. This may simply be because cheaper boxes aren't made to the same standard. My thoughts are that it's a combination of that and the fact that the boot floor and bumper create a little echo chamber on four sides of the rear box which amplifies the sound. I'm going to have a go with various sorts of muffling and see if it makes a difference. So in short, how much do you want to pay and what (beyond getting through the MOT) is your preferred result? __________________ Conformity is not morality. Consensus is not truth.

3rd August 2016, 07:32	#2
john2443 Avid contributor ZT CDTI / 1951 Healey Tickford Drop Head Join Date: Jun 2014 Location: Brighton Posts: 207 Thanks: 19 Thanked 28 Times in 23 Posts	Gun Gum might work and hold on long enough for the MOT, it might work for a year but might fall out in 10 mins!

3rd August 2016, 08:50	#3
Monty Hotspur Avid contributor Rover 75 Saloon Join Date: Dec 2015 Location: Berkshire Posts: 110 Thanks: 3 Thanked 24 Times in 22 Posts	Gun Gum will struggle to stay in place - the gas pressure will likely blow it straight out. If you use it and cover with an exhaust bandage then you will have a better chance of it sealing up and staying in place until at least after the MoT. However, if you are going to all the trouble of replacing the cat then the backbox is an easy 10 minute job.

3rd August 2016, 09:09	#6
Sheraton Posted a thing or two Rover 75 1.8t Join Date: Oct 2015 Location: Edinburgh Posts: 1,377 Thanks: 384 Thanked 409 Times in 267 Posts	cheers folks i'd ideally like to change the backbox (it will be replaced asap) however i don't have funds to do this before the mot so off to halfords for Gun Gum it is we'll see how it goes.......i figure if i do it now, i'll have a couple of weeks to see if it does the job and holds up - if not, i'll have a bit of time to see what i can do r.e replacement backbox. Paul........