Piston Slap: Deep Six the 626?

Sajeev Mehta
by Sajeev Mehta
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piston slap deep six the 626

Joey writes:

Hello Sajeev,

I’ve been a reader of yours for years and greatly enjoy your style. (Woot! —SM)

My question is about my ’97 Mazda 626, with a hair over 215,000 miles on it, that’s been in my family for its entire life. It’s reliable, economical, and generally in good condition.

However, I am up for a registration renewal in October, and I need to complete an emissions test. I figured that it would be a good idea to check up on the codes behind the check engine light. The codes came up as an evaporative system and catalytic converter errors, which are both emissions fails.

I think that there may be a leak in the exhaust (I can hear a sort of rasping occasionally with the windows down), which could be the cause of the catalyst code, but I wouldn’t know what to do with the evap system.

I put a set of new (cheap) tires on it about 6 months ago and put in a new starter two months ago. How much further should I go, and how much should I spend on a car with so many miles?

Sajeev answers:

I love that vintage of 626, which will explain the following answer: At this age and mileage, I suspect your check engine light repair is minor. Granted, it’s crucial to provide the actual code (not what it means), but I shall remain positive that it’s an easy fix.

Start with a basic tune-up and new vacuum lines. The tune up includes new oxygen sensors if they are 100,000+ miles old. Vacuum lines are an oft-neglected reason for catalyst/lean exhaust codes, and are a cheap (but labor intensive) fix. Also usually cheap are some of the rubber fittings (like the one that holds the PCV valve). Those are only available at a dealership, but some are often duplicated as plastic fittings.

If the exhaust leak is between the catalytic converters and the engine, then yes, that must be addressed to fix the code. Not that you’d refrain from fixing it otherwise … riiiiight?

And that goes back to your main query: how long do you dump money into this Mazda? The mere fact you wrote to me a fairly warm tale implies you like it more than anyone else with $1,000 and a need for a cheap beater. Provided I’m correct regarding the diagnosis/repair, it’d be foolish to not let the Mazda limp along for another year. Or five.

Best and Brightest?

[Photo courtesy: Shutterstock user Bjoern Wylezich]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

Sajeev Mehta
Sajeev Mehta

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  • Speedlaw Speedlaw on Feb 03, 2016

    yup, my life right here. In my area of NY, a lit CE light = fail. I've nursed one spotty cat (works but lights off late) through two inspections in one car. My 13 year old car is gonna need new hoses to clear a lean fault but I have the summer to take the engine apart to get to those buried hoses. The car hasn't left you walking, so that is a very important bit. Get nn your brand specific forums. Nothing new ever happens, so I'm sure that your error codes are dealt with by others who will discuss a DIY. I once got four error codes on my 3 series. Forum says accordian intake hose at back of manifold is shot. Feel around, and fingers go through rotten hose. Even with a good visual inspection, would never have found these cracks...thanks e46fanatics ! Even if you don't DIY, at least you'll know how much work you are looking at. My basic rule...if it doesn't leave mama walking, and the repairs are less than the state tax on a new ride, fix it.

    • Macmcmacmac Macmcmacmac on Feb 07, 2016

      Funny, when I first moved to Ottawa, I had to get my 1987 Mustang LX 5.0 emissions tested and it passed despite two completely rusted away air injection lines. I guess there are a lot more failures with the CEL method. Ontario has recently taken that approach, as not enough cars were failing ($$$$$$$).

  • Macmcmacmac Macmcmacmac on Feb 07, 2016

    Dilly of a pickle. Sort of the same situation my friend was in with her 1998 626. Generally reliable, it nevertheless was beginning to suffer from regularly occurring small failures. The final straw was the brake lines blowing on a trip home from work. I figured I could do them cheaply enough but when I couldn't even find where they disappeared to once they left the master cylinder I decided to hell with it. I had been the main wrench on this car for 12 years as she is not what you would call financially comfortable enough to send it to the dealers for anything but exhaust work. The fact that I had come out and found the entire passenger side rocker panel hanging on by only the paint one day convinced me the car was coming due for knackering. It was too bad, as it had only 120,000kms on it. I could see a panicked phone call coming in the near future though, this time with rusted through fuel lines and gas everywhere, so it was time to call time. She regarded it as a reliable vehicle, but for the amount of miles on it, I'd say 3 alternators, two CV joints, a complete exhaust system, half a dozen sway bar end links, and rusting through wasn't exactly stellar reliability. The tranny gave me cause to worry as every once in awhile it would engage drive with an alimighty THWACK. Probably the aforementioned pressure problem. Some Lucas tranny treatment seemed to help but I couldn't get the thought of plastic pistons inside there out of my mind. The engine was ungodly silent at idle though, and the car itself was remarkably fuel effiicent, at least compared to her old 16V Volvo 740 wagon.

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