Lack of power on M13A engine

Just read this for the first time and what an emotional rollercoaster- it's the cat, then the brakes and now the rear axle!

Let's stop a moment and start looking at this with some tests to provide some evidence of what is occurring, rather than a load of guesses.

Generally if a cat is blocked you lack power and it might struggle to rev. It might make rattling noises too. These depend on how it's blocked and how much it has broken down inside. It will always be down on power and usually struggles to rev when under load.

Changing a cat yourself for a cheap aftermarket one to my mind is just hassle unless you have access to heat as the bolts will be rushed badly. They're not that expensive fitted at a garage.

So if you have these symptoms, they are not linked to the brakes or the rear axle.

If a brake calliper or wheel cylinder is seized, the wheel on that corner will usually feel hotter than the others after a good drive. If really seized it will be really hot to the touch.

Jack up each wheel indepently and chock the fronts when you raise the rears as you'll need to take the handbrake off. Spin each wheel whilst off the ground. The fronts should just spin freely, the rears will spin but you'll have some drag from the transmission.

If one is seized it will not spin and will require effort to make it turn.

As for the rear diff, generally, if it's not whining, it's fine. Undo the filler plug and see if it needs more oil. They use EP90. Get some if it needs topping up and if you buy the 1 litre bottles from Halfords, they have a great pull out spout that you pop in the filler hole and squirt it in with until it runs out of the hole.

If it doesn't whine when driven or make awful grinding or banging noises when you're testing the brakes at the rear, I'd say it's fine.

If you can't get the diff filler plug undone by using a ratchet, which isn't really the exact size as it's 10mm, not 1/4 inch, try a set of mole grips around the outside and tap them round with a hammer.

I hope these tests help you move forward and take the guess work out of the matter.

Kirkynut

I'm guessing that the crank sensor made no difference and I wouldn't have thought it would. They generally work or don't work. The engine won't run if it's broken.

The engine won't sound any different if the cat is blocked, it just won't want to rev under load.

5mm wheel spacers won't make any difference to seized brakes heating up the wheel. They're made of metal that transmits heat and are only 5mm.

Have you jacked up each wheel like I said?

Kirkynut

I've just gone back over this to see if I've missed anything. So you've put on 195/80/15 extreme mud terrain tyres I see.

They will have a significant impact on the car. The drag they cause is massive, hence the noise they make going down the road.

Kirkynut