Piston Slap: Feelin' Rotten Sans Seam Sealer?

Sajeev Mehta
by Sajeev Mehta
piston slap feelin rotten sans seam sealer

TTAC Commentator Calgarytek writes:

Hey Sajeev,

I enjoy reading your posts on TTAC. This one is a chassis related question and concerns rear quarter panel rust issues on old school Hondas.

I’ve got a 2000 Civic SiR and I’ve poked around the rear wheel wells to figure out why that may be. It seems that Honda didn’t seal the rear quarters well enough. There is no sealant present on the inner skin of the outer portion of wheel well. The outer skin just tends to ‘fold’ into the inner well and just ‘sit there’ as exposed metal.

The question is – would applying seam sealer to the above mentioned locations protect the quarters? If so, can you recommend a brand?

If you’re wondering, I’m helping my younger cousin buy a non-rust-belt-based 2000 Acura EL. We’re planning to winterize the vehicle during the summer time when he eventually gets it.

Sajeev answers:

Thank you for your note, and for reminding us Americans that cooler Hondas are available outside of our borders.

Before answering, one point of clarification: what you see isn’t “exposed metal” waiting to rust. As part of the assembly line process (all?) manufacturers dunk their cars into a rustproofing bath to minimize corrosion. Peep this vid:

Also note how BMW’s machine applies seam sealer after the rustproof dunk. But in the case of Honda rear wheel arches…well, I wonder if any manufacturer uses seam sealer there. It’s gotta be a messy proposition.

On to your question: if you are positive you’re applying seam sealer to a rust free, dirt free, dry and solid meeting of two panels, by all means go ahead! My big concern is trapping dirt, water or anything else that can cause the panel to rust under the seam sealer. Hence why the rustproofing “dunk” at the factory is so cool.

A company called POR-15 makes a host of products for the pre-seal, I do not know of an alternative that works as well. OTOH, seam sealer is available from a host of manufacturers sold by even more vendors. Not being a body man by hobby or trade, I’m offering this as a guide instead of making a recommendation.

There you go, Best and Brightest.

[Image: Shutterstock user Sirinn3249]

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.

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  • Jgwag1985 Jgwag1985 on Mar 09, 2015

    POR15 waste of time. Used it per directions (all steps correctly followed) and it peeled off after a year. I had the Krown process performed on a car and was impressed. It is a yearly process though...............but I could not stand the car and after a year I got rid of it. But I will use Krown (Carwell same thing) on my Jeep when out of storage......Hagerty insurance did an article on undercoating, and recommended Krown/Carwell products. Again it must be done annually, but it's worth it.

    • DeadWeight DeadWeight on Mar 10, 2015

      POR-15 was the be-all, end-all, miracle solution to rust prevention 3-4 years ago. Fast forward to today, or even a year or two ago, and horror stories abound regarding the crap just coming off in sheets - even when metal/surface prep directions were adhered to religiously, on everything from truck beds, to frame rails, and on everything from trucks, to passenger cars, to tractors and combines.

  • Gzuckier Gzuckier on Mar 10, 2015

    Just wondering; might the rust through not be worse if the steel is thinner, because of using high strength steel?

  • MRF 95 T-Bird The hideaway headlamps on these and other Ford vehicles of the era could have issues mostly vacuum related. Usually the vacuum hoses that ran to the actuators would deteriorate. The “coffee can” reservoir which was mounted in the front header was rarely an issue because it was protected from the elements. The other coffee can reservoir used for the HVAC controls and actuators and mounted under the passenger side wheel well had a tendency to rot away. I once replaced one on my 70 Mustang when I noticed that the vents were acting janky. Later model Fords like Fox bodies used a durable plastic globe shaped one. The radio on these 69-70 full-size Fords mounted on the left side of the aircraft style instrument cluster within the drivers touch probably disappointed many young people. “Mom will you change the station?” “Andy Williams is so square”.
  • MichaelBug For me, two issues in particular:1. It can be difficult for me to maintain my lane on a rainy night. Here in southeastern PA, PennDOT's lane markings aren't very reflective. They can be almost impossible to make out when wet.2. Backing out of a parking space in a lot with heavy pedestrian traffic. Oftentimes people will walk right into my blind spot even if I am creeping back with my 4-way flashers blinking. (No backup camera in my '11 Toyota Camry.)Michael B 🙂
  • Tagbert When you publish series like this, could you include links to the previous articles in the series so that we can follow through? Thank you. Edit: now I see a link embedded in the first paragraph that goes to the previous story. It wasn’t clear at first where that link went but now I understand.
  • DungBeetle62 When you're in one of these, you life in a state of constant low-level nervous about 90% of the time. But that other 10% kinda makes up for it.
  • Garrett Instead of foisting this problem on the car companies and the people who buy cars, make those who possess liquor licenses and those who purchase alcohol take on the economic cost of this problem.
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