By on January 23, 2012


C.V. writes:

I am a mechanical engineering student looking to learn how to work on cars.

My friend has given me the opportunity to take his 1988 Mazda B2200 extra-cab 5-speed. When I drove it, I saw why. The catalytic converter has broken off, and apparently pieces of it are in the exhaust. Would it be possible to just replace the catalytic converter, or should I replace the whole exhaust?

Also while driving it, there is a weird problem. About 10 or so minutes after startup and driving, it starts bucking back and forth as if I was engaging and disengaging the clutch. Any idea as to why that is happening? Theoretically the truck could drive even with this problem, but I don’t think it’s safe or good for the truck. What should I do?

Sajeev answers:

It wasn’t long ago that I was an mechanical engineering student looking to work on cars.  Hell, it’s way more fun than a semester of Thermodynamics, Solid and Fluid Mechanics! So what’s my advice?  Join the Society of Automotive Engineers (SAE) as a student and join the local chapter in your college.  The SAE chapter at the University of Texas changed my life, in a good way. And if you don’t have a chapter?  MAKE ONE!

Oh wait…you wanted advice on the truck, not your career. My bad.

The first problem is pretty easy, replace the convertor. Or not: eventually the loose bits of honeycomb inside will stop playing Super Breakout with itself, exit stage left, and it still might pass an emissions test.  If not, any exhaust shop can slap in a new one, and I just Googled one for $270 that’s a direct replacement.  I am sure you college kids use Google all the time, why not for a sweet little truck?

The second one is usually a combination of a poor gear change technique and a lack of fuel.  Or maybe too much fuel.  Does it buck less if you give it more gas and take more time to let out the clutch?  Problem solved. If not, I’d recommend rebuilding the carb, seafoaming the motor (at your own risk, see YouTube for reasons why), and testing the fuel pressure.  Actually not in that order: start with fuel pressure, then maybe learn how to work on a carb.

Or convert it to a later-model EFI setup! Or even better, LS1-FTW!!! You are an engineer for a reason!

Send your queries to [email protected] . Spare no details and ask for a speedy resolution if you’re in a hurry.

Get the latest TTAC e-Newsletter!

12 Comments on “Piston Slap: Playing Super Breakout by Itself?...”

  • avatar


  • avatar

    Bucking coming on and off throttle while in gear? The drivetrain could be moving around inside the car if you have worn or broken mounts. Could be flywheel related also.

    Your shifting isn’t causing it directly, but someone’s harsh shifting probably contributed to the wear sometime in the past. On the other hand, this truck is old and all that stuff needs replacing anyway.

  • avatar

    Sorry Sajeev, the proper swap for a B2200 is the F2T 12 valve turbo our of a probe/mx6/whathaveyou. This engine swap offers the right combination of deceptive difficulty (It’s the same block, how hard could it be?), incredible costs (a new turbo costs WHAT!!!???), and lack of results (All that, and it’s only putting 180 hp to the wheels!?!?! I should have done an LS-x).

    If you do the right thing right away, how would anyone learn anything?

    • 0 avatar

      The most interesting swaps for these is a 13B. Mazda engineered the 86-92 trucks to take a rotary engine. The Frame rails are set wider apart than the earlier trucks, which makes the swap easier than on the earlier trucks. (The REPU had wider set frame rails as well.)

      A 12A drops right in, but is a bit low on power for these trucks. A 13B will also go right in, as long as you make sure to procure a front cover from an 84-85 RX-7 GSL-SE for the correct motor mount position. The manual transmission (Type-M or Type-R, I forget which) is shared with the RX-7 – just need to swap the bell housing. You can keep your driveshaft, and if you want an LSD, the pumpkin out of a GSL-SE will supply it – just keep the truck axles as you’ll need them to keep the track correct and the 6-lug pattern.

      Since these trucks came with a carb, you can easily stay carb with the 13B which will make the whole project much easier. With the right bits, you can manage 160-180 hp without porting the motor, which isn’t earth shattering but is almost twice what the truck came with, and is just about right for a truck that weighs 2500-2800 lbs, depending on configuration and options. The 13B is lighter than the F2 engine it came with.

      FWIW, the F2T is actually a bit harder to fit since the firewall on the truck is where the distributor wants to be. If you want to stay with that engine series, an FE3 out of a Kia Sportage (yes, really) is a good starting point. I you can get a genuine Mazda FE3, even better, as they have forged internals and are good for 170hp naturally aspirated, but they were never sold in the US and not particularly common engines in any case.

      The LSx gives the best bang-for-buck, to be sure, but the 13B swap is about as painless as it will get.

      Back to your original question… If the truck is in ok shape, a new cat is a no-brainer. $300 parts and labor should do it. These have Nikki electronic carbs that are notoriously difficult to rebuild. If you have a carb issue, I would go with one of the Weber downdraft kits they make for these 32/36DGEV or something like that.

      I had one of these with the Weber, a header and a glass pack, and it sounded remarkably like an old British sports car. Very rorty. Those mods woke it up but it was still fast by no means. These can be made to handle pretty well, too. The tin worm ate mine, like most of them. I would love to find a nice, low mileage, rust free example from out west to do the 13B swap!

  • avatar

    Oxygen sensor is most likely shot. You can check it with a voltmeter, it should switch from 5 volts down to .45 when running, or you can retrieve codes from the computer.
    Black plugs and poor mileage, along with black exhaust are a giveaway.

    The converter is a common problem with Fords from that era, if you don’t have emissions you can try a test pipe in it’s place.

  • avatar

    If I remember correctly from my brother in law’s 87 B2000, the cat is directly bolted to the exhaust manifold. Not difficult to change really.

    All I remember of that truck was it was fun to drive, slow as molasses, had the weirdest emission controls and sported a 2 or 3 barrel carb. The 2200 was a bigger version of that 2.0. He kept it till the clutch wore out and traded it for a 95 C1500 in 99.

    The 2600i was where it got interesting and everything swapped sides.

  • avatar

    Can’t say about your state but in Texas you become exempt from emissions testing next year. My guess is that you can’t pass. Have had to read some about it recently and the cat could be broken up by periods of excess fuel in the exhaust. They only process so much and how much time that takes depends on the engine and it’s tune. It can go fast. Replacing it is a good idea if you have checked for underlying problems. If you have excessive hydrocarbons I think it’s throwing good money after bad.

    If you basically have good engine internals you have found something you can consider a keeper. It’s probably cheaper to keep than to buy new if you know a good independent mechanic. If you don’t – you need to. My 87 Nissan now sets in a back pasture with a frozen engine. It had over 300k on the odometer before it decided to croak.

    For a college student you have one of two things here. It is either an economical answer to long term transportation while you are becoming a well comphensated member of society, or, it’s a money pit. Depends on the truck.

  • avatar

    The bucking almost sounds like the exhaust pipe/muffler is clogged with bits of the catalytic converter, and is creating alot of back pressure. We had a Nissan Quest that did something similar when hot, it got worse to the point where it wouldn’t move. Took the exhaust apart and cleaned all the pieces out.

    • 0 avatar

      +1; same thing happened with my 1999 Accord when it had 150k or so miles on it. It had given a check engine light that I ignored because of a year’s worth of spurious indications before that.

  • avatar

    I had a Nissan truck, 1983, with a carb; anyway, that + a number of other 80s vehicles would “jerk off” if trying to coast with ANY amount of throttle. The only way to coast in gear smoothly was to take foot OFF the throttle.
    Having said that, something made the converter come apart; better find out what.

Read all comments

Back to TopLeave a Reply

You must be logged in to post a comment.

Recent Comments

  • Matt Posky: @28-Cars I know it. There’s already a cadre of analysts claiming 2024 will be the year things go...
  • jack4x: Perhaps I am sheltered. But I don’t come across empty shelves when shopping. I haven’t noticed...
  • Matt Posky: Productivity has increased steadily since the 1940s, compensation stalled around 1974 barely keeping pace...
  • dal20402: Inflation only hurts most wage earners to the extent that wages and housing prices don’t rise to...
  • 28-Cars-Later: “BMW says they’ll be clients with a long history of owning 7-Series machines with a V12 under...

New Car Research

Get a Free Dealer Quote

Who We Are

  • Adam Tonge
  • Bozi Tatarevic
  • Corey Lewis
  • Jo Borras
  • Mark Baruth
  • Ronnie Schreiber