Repair or scrap / break

We took the Jimny to a garage for diagnosis this morning. His machine couldn’t read any fault codes but he found a split vacuum pipe on the engine. He suggested that might have affected the fuel air mixture and that he thought the exhaust / catalytic converter may be choked. He also found that there was a definite leak in the exhaust around the area of the lambda senso or manifold to front exhaust pipe joint. Both fixings were extremely tight and he didn’t want to risk snapping something when it wasn’t booked in today to have more work done. So another booking would be needed to investigate further.

Does that suggestion of a choked cat and leak seem feasible as the cause of our problem?

It does, it's not uncommon for the cat to disintegrate and bung the rest up.

Thanks Lambert.
It’s not something I’ve come across before but I’ve largely driven diesels for 20 years and recent petrol cars didn’t have this problem.

When you say bung the rest up do you mean the silencer(s) and if so, does that mean I’ll need a full new exhaust?

The cat will tend to fail upstream first and the debris will then clog the remaining part of the cat. Usually once replaced the residue will find it's way out of the tailpipe.

Took it back to the garage this morning as they’d suggested removing the lambda sensor briefly to see if it gained power which would confirm the blocked cat suggestion. They couldnt get the exhaust manifold to front pipe bolts undone but neither could they get the lambda sensor out. After a breaking release feeling the nuts / sensor went tight again suggesting the threads were getting chewed up.

With a suggested difficulty in getting parts for a 25 year old car they suggested a bit of a workaround by cutting the exhaust down pipe and sleeving it afterwards. So, a temporary cut to check whether power improves then possibly sleeving a new cat pipe on.

I’m reasonably convinced it is a blocked exhaust now as there’s blowing at the front as the pressure gets out there instead of going down the exhaust pipe and it’s quite fumey in the car too.

I did say that I could get a new lambda sensor if needed but perhaps another option might be to buy a second hand exhaust manifold which might not have issues unscrewing the cat, and use new bolts for the manifold to front pipe joint. There’s two currently on eBay but they may have the same issues as the cat is still fitted. A question is, is the exhaust manifold the same on all Jimny engine types? Ours is the early G13BB SOHC engine.

Paul4A wrote:

A question is, is the exhaust manifold the same on all Jimny engine types? Ours is the early G13BB SOHC engine.

No it's not - generally speaking, the manifolds are going to be different for every engine type - the M-series manifolds I believe will interchange, but the G-series won't work on an M-series or vice versa.