1.7 340 "cat" model exhaust probblems

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Nuttyjimbob
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1.7 340 "cat" model exhaust probblems

Post by Nuttyjimbob » 01 Nov 2014 10:55 am

Hi everyone Ive just brought a 340 1.7 cat model and when i picked it up it wasn't running to good. Idled and started fine sounded good to the ear. but when revs gained it made a loud hissing noise and tried to stall. first thought was air intake. so air filter off because it was pretty dirty and tried again. apart from sounding awesome it still did the same lol. i then noticed that the intake to carb gasket had been repaired and Ive read that they have warping problems so i had it running and got it to max revs before it stalled and sprayed WD round the gasket and it wasn't leaking. so we thought give it a good drive up the the road and see what happens. got and 10m out the drive and it stalled and wouldn't start lol but when the engine had stopped the loud hissing still carried on. bang! problem found it was the exhaust. so pushed in the drive and thought only thing it could be is the cat had fallen apart and caused a blockage it the silencer. took it off from the manifold and started it up. sounded like a tractor but it fixed the problem and went surprising well. so i open up the cat and both the silencers, pulled all the blockages out and welded it back up put it on the car and had the same problem again! now there is now no blockages and its straight through so i have no idea what it could be and my only suggestion would be pipe diameter. could it be to small? possibly from a smaller engine size car? as the exhaust looked pretty new.
i work for a exhaust company and never come across this being a issue and causing so much loss of power. it could barely reach 25mph lol. i know with some engines back pressure can be a issue but this it way to much! and Ive never come across this being a such a problem. anyone on here had a similar problem with exhaust problems with pressure build up? or have any ideas? sorry for the long essay but it gives to you a good idea of whats going on.

Ride_on
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Re: 1.7 340 "cat" model exhaust probblems

Post by Ride_on » 01 Nov 2014 01:39 pm

Never heard of this before, and I really doubt pipe diameter would be an issue. I bought a glt with a 340 exhaust on it once, it just lacked top end power a little. The 1.4 and 1.7 exhaust are same AFAIK.

Are you sure you have accessed all the possible blockage areas? Could be something caught in a bend, try feeding a welding wire through.
1980 345 DL_______1987 360 GLE (project car restored to GLT spec and B230FT'd)
1984 360 GLT______1987 360 GLT
1983 360 GLS______1989 360 GLE
1985 340 GL_______1986 340 1.4
1985 360 GLS______1995 940 SE 2.3 Turbo Estate (daily)
1987 340 GL 1.7

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Nuttyjimbob
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Re: 1.7 340 "cat" model exhaust probblems

Post by Nuttyjimbob » 01 Nov 2014 02:29 pm

thanks for the reply. after thinking about it there might be a block still. but when testing it to see if there was a block still, it seem to flow through. ill have another look later. ill prob just make a stainless one for it seeing as i wont cost me anything but materials lol. just having the time is the problem :/

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bogbasic
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Re: 1.7 340 "cat" model exhaust probblems

Post by bogbasic » 01 Nov 2014 10:27 pm

How's about exhaust valves, cam or even timing setup?? Also, head gasket {^¿^}
1988 340 1.4 GL, 218k, 5 door (Grey Bess). Gone to CBA.
1991 340 1.7 GL, 64k, 5 door, petrol blue (Deep Blue).
1988 360 2.0 GLE, 140k, 5 door, ocean blue metallic (Blue Bess).
1989 340 1.7 GL, 108k, 3 door (Red Ness).
More info here!

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Nuttyjimbob
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Re: 1.7 340 "cat" model exhaust probblems

Post by Nuttyjimbob » 02 Nov 2014 11:29 am

bogbasic wrote:How's about exhaust valves, cam or even timing setup?? Also, head gasket {^¿^}
I thought about that but when we took the exhaust off it ran fine. I will be checking timing, just waiting on all my service bits atm then I'll be giving it a once over. :D

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Nuttyjimbob
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Re: 1.7 340 "cat" model exhaust probblems

Post by Nuttyjimbob » 02 Nov 2014 11:34 am

I'll be making a exhaust for it in the week if I have time.

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bogbasic
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Re: 1.7 340 "cat" model exhaust probblems

Post by bogbasic » 02 Nov 2014 01:35 pm

I was thinking about the times I have run an engine w/o the exhaust - the noise is so bad I can only run it for few seconds before my nerves give up but if you ran it for a comparable amount of time then I'm sure you're right.

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Nuttyjimbob
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Re: 1.7 340 "cat" model exhaust probblems

Post by Nuttyjimbob » 03 Nov 2014 09:57 pm

started on making a new exhaust today. used a old can that never got used and some spares from another job.
just got to weld it up now its tac'ed together
Image

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Nuttyjimbob
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Re: 1.7 340 "cat" model exhaust probblems

Post by Nuttyjimbob » 05 Nov 2014 12:58 am

New exhaust welded and fitted and it has sorted all the problems! Went for a side exit just because it was easy. plus it sounds awesome!

Image
Image

and heres a video of the sound
https://www.youtube.com/watch?v=R49zQQA ... e=youtu.be

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bogbasic
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Re: 1.7 340 "cat" model exhaust probblems

Post by bogbasic » 05 Nov 2014 04:55 pm

Man, that is an evil exhaust system.
1988 340 1.4 GL, 218k, 5 door (Grey Bess). Gone to CBA.
1991 340 1.7 GL, 64k, 5 door, petrol blue (Deep Blue).
1988 360 2.0 GLE, 140k, 5 door, ocean blue metallic (Blue Bess).
1989 340 1.7 GL, 108k, 3 door (Red Ness).
More info here!

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Nuttyjimbob
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Joined: 01 Nov 2014 10:01 am
Location: Bucks

Re: 1.7 340 "cat" model exhaust probblems

Post by Nuttyjimbob » 05 Nov 2014 06:08 pm

bogbasic wrote:Man, that is an evil exhaust system.
Sounds better then I thought haha. it will be for sale soon as I'm changing engines in the new year

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