Datsun Roadster Forum-311s.org

SO, it was time to tear the engine of the red roadster down to find the source of the noise that caused me to shut it down.

Oil was like salad dressing, there was a teeny piece of metal embedded in #1 cylinder head piston, which also of course damaged the #1 piston. And you won't believe what I found in the thermostat tower.

Bearings look nice and clean.

Head unusable (or spendy to repair) - Harlan has a replacement (Thank you)

Need to have new head decked - who is using whom in the Los Angeles Area now that Mark has retired?

Ah! The joys of a 50 year-old car.

I can do your head but I am in Las Vegas. Any idea where the metal in one came from?

I hope that you don't find too much more evil in your bores!! I had some similar interior rust in mine after it sat indoors for 14 years. It had to be bored .050 to clean them up. I run a dehumidifier now.

keith0alan wrote: ↑Wed Jun 03, 2020 7:18 am I can do your head but I am in Las Vegas. Any idea where the metal in one came from?

Looks like a piece of valve seat is missing from the intake. The head can be fixed easily.

Pete, I took my head to Metric Engine in N. Hollywierd a couple years ago. He specializes in heads and turn around was quick. I had good luck with my daughters Volvo head so decided to take my U20 in. Older old school gent who seems to know his S#*t.

Those pieces look like part of a compression ring.

Could those bits a metal be from the cylinder wall itself? Have you rotated the crank 360 yet? How else would things fall into the bore? Was this the maroon red car you brought down from up north?

todd lorber wrote: ↑Wed Jun 03, 2020 11:50 am Those pieces look like part of a compression ring.

That was my first thought, then I saw part of the valve seat is missing.

todd lorber wrote: ↑Wed Jun 03, 2020 11:50 am Those pieces look like part of a compression ring.

Yes I agree they do, but yet the piston land appears to be intact.

Valve seat, or another possibility would be that it sucked something in and broke the seat while eating it.

I just saw that Autozone now has a bore scope included in their loaner tool program. That could be handy, though the engine is mostly torn down at this point
Linda

Get th e wizzer out with a wire wheel and clean the carbon off the piston tops to see the damage

well done Phil - you discerned the issue.

Exhaust valve seat on # 1

Don't know how these things break, but it did and screwed up the head and #1 piston (the latter not being a problem, having quite a few).

I was running at about 75 MPH when it all went south (technically, I was going west)

Any idea what might have caused this??

That seat looks pretty tired. My guess is that the seat was thin and cracked, and with further driving it just failed. The bright side is that you didn't drop the seat and really make a mess of everything.

Will

The valves look to be a little deep in the seats indicating they have a bit of wear on them. Also, the the picture of the failed valve seat shows that the retaining punch peen at that location is a little too close to the edge. Combination the wear and a localized stress riser in the edge of the valve seat material is more than likely whats had caused a failure crack at that point.
No worries, Both valves and seats are still available.

Cheers
Ray B.