Cracked exhaust manifold

[Alan c]

Having used the newly aquired Marlin a lot I found the exhaust was getting louder - did not take long to find the crack in the manifold. Patch up done, but needs a new manifold as it has generally past its best and the design (flexibility) of the exhaust could do with improving if its not to happen again.

I thought I would get advice from the fine minds of the MOC members to see it there is a tried an proven design (and parts suppliers). Details of car:

Marlin Cabrio with Sierra running gear, 2.0l OHC engine, Exhaust manifold is 4 into 2 into 1 heading off into a single box and single tailpipe. I was planning to just change manifold and put in a flexi where it joins the box (and add one more strap support). Box and tailpipe look like Birmingham's finest st.st items - so OK.

Any comments to my master plan???

[chris_cussen]

Re: Cracked exhaust manifold

Is it a Pinto or DOHC 8V engine?

After market bits for the DOHC are rare, but there are plenty for the Pinto engine.

[cameronfurnival]

Re: Cracked exhaust manifold

4-2-1 pipes can generate more power but the cast manifold maybe more longer lasting - if you can get an original manifold try and get part of the down pipes too, makes it easier to cut and attach the flexible pipe to. The I4 engine (the DOHC) is a pain to get anything aftermarket for but as Chris says, there's plenty for the pinto.

[keith_h]

Re: Cracked exhaust manifold

I had exactly that problem with my Sierra 2.0i DOHC manifold which is the same configuration as you describe. Every time you gun the engine it twists slightly and according to how the rest of the exhaust is configured and bolted down it will put a strain on the manifold . I solved it by having an specialist exhaust company weld the crack up and weld a stainless steel flexible and pipe to the bottom of the manifold. Not cheap but touch wood and 20,000 miles on, it is still OK.

[danny_nelson]

Re: Cracked exhaust manifold

Hi Alan,
I know your Cabrio has SOHC engine and I would guess the manifold , and the rear stainless box and pipe were as supplied by Marlin. After market tubular manifolds are very much available for the pinto, Burton, Rally design to name just two, but there are many. However be sure of the swept angle at the rear and the clearance etc. A flexible joint is a good addition to your system. You should have no problem finding the parts. You could as suggested above replace with a Ford cast manifold and single down pipe, but the tubular one gets it all away better.
Danny.

[Alan c]

Re: Cracked exhaust manifold

Thanks guys - just catching up (work keeps getting in the way) yes its a Pinto SOHC as Danny rightly points out. All the good advice taken on board (especially the swept angle as I have not realised they varied).
I had considered welding but in truth the item is past its sell buy date and really needs renewal.

[CABRIOBOB]

Re: Cracked exhaust manifold

Alan

I have a new Ashley 4-2-1 exhaust manifold for sale that fits a 2lt Pinto engine fitted to a Cabrio. Pm me if interested.

Having used the newly aquired Marlin a lot I found the exhaust was getting louder - did not take long to find the crack in the manifold. Patch up done, but needs a new manifold as it has generally past its best and the design (flexibility) of the exhaust could do with improving if its not to happen again.

I thought I would get advice from the fine minds of the MOC members to see it there is a tried an proven design (and parts suppliers). Details of car:

Marlin Cabrio with Sierra running gear, 2.0l OHC engine, Exhaust manifold is 4 into 2 into 1 heading off into a single box and single tailpipe. I was planning to just change manifold and put in a flexi where it joins the box (and add one more strap support). Box and tailpipe look like Birmingham's finest st.st items - so OK.

Any comments to my master plan???

[Alan c]

Re: Cracked exhaust manifold

The replacment exhaust manifold I wrangled from CABRIOBOB for a very reasonable sum (thanks again) was eventually fitted, 5 months later (the cracked one hung in for that time). Working abroad and using the Marlin as my daily drive when I return for a weekend each month meant I had to let the local garage fit it (while they MOTd and serviced it - it got through with only the need for a new indicator stalk assembly and a back brake cylinder).

The big surprise was how much better the car runs (smoother and more power). Even better than the improvement I achieved when I had it on a rolling road mid last year. So I investigated a little. The obvious thing was that the exhaust manifolf gaskets were not fully alligned with the ports and thus restricting the gas flow by at least 10% by area (see photos). I guess the new ones lined up better and I effectively got an instant equivelant to a gas flowed head.



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