Canadian Nissan Truck Club

How common is it for the catalyst to break off on the manifold mounted ones and get sucked into the motor? My shop that is swapping the engine says one of the cats is damaged and it likely scored the cylinder walls.

How the hell can the exhaust suck the catalyst into the engine???

I googled it. Apparently it is true. I saw it and it has some chunks missing and they are nowhere to be found...

If the catalyst is physically broken, then yes, that is a possibility.

I have seen it multiple times.

Exhaust pulses as the engine goes through its 4 cycles.

During that moment it pulses, there is negative pressure in the exhaust.
Being a manicat, the catalyst material is right there at the engine, and can be sucked back into the engine.

To tell how badly, you could do all the work of pulling the head, or trying to look with a borescope through the spark plug hole.

Well I'll be...

Do a compression test?

I already know two of the cylinders on that side have low compression. Going to source an aftermarket cat and move on. The old engine actually ran well, just burnt a ton of oil.

Scored piston walls will cause high oil consumption.

Burning oil causes plugged cats

It's a vicious cycle

I probably made it worse by just driving it anyway. I had to add about a Liter of oil every 200km haha. I was starting to just put the used oil from my pathfinder in it.

Adam wrote:I probably made it worse by just driving it anyway. I had to add about a Liter of oil every 200km haha. I was starting to just put the used oil from my pathfinder in it.

Wow, that's almost as bad as my old jeep. 5L per tank of gas... (I went through as set of spark plugs in a week.)

Crap that sucks. The truck is awesome. Is there compatible engine swap?

I purchased a used VG33ER engine from someone in this group that is getting put in tomorrow. I had it compression tested before and I got to hear it run in the truck before it was pulled.

It burned way less if you only drove in the city and kept your foot out of the pedal. But I drove it to work for 3 days and on the third day, the dipstick was dry. I was driving 30k one way at that point...

Adam wrote:How common is it for the catalyst to break off on the manifold mounted ones and get sucked into the motor? My shop that is swapping the engine says one of the cats is damaged and it likely scored the cylinder walls.

Yup, Titan's are known for this one too. Nissan manifolds are the gift that just keeps on giving.

My pathfinder never had this problem. Then again it has only 1 cat and it probably passes with the same cleanliness as an X that has 4.

Miner wrote:Nissan manifolds are the gift that just keeps on giving.

To Nissan.

As a (not so) funny side note. The "new" engine had aftermarket manifolds, and one was already cracked. I made the choice to have them reuse the manifold from the old motor. We will see if that bites me in the ass or not. If I had the extra 500 dollars in the budget for this thing I would have just bought headers.

Update, the truck is done. It runs great and instead of putting a new cat in I just hollowed out the bad one and will put headers on it at some point. No need to worry about the e test as I got it to pass before the swap...

Cost me a little more than I wanted but it has a new clutch, all new gaskets, oil pan, belts, etc. Body is mint so that is the only reason I proceeded.

Good to hear!