TD .09 - Something interfering with the rotating assembly

**RknRusty** Wed Jul 04, 2012 10:48 pm

This is my first non-.049 engine. Other than oiling it when it arrived, I just took my first close look at it today. It seems very clean, good compression, no SPI and a tighter pinch than I expected approaching TDC. I haven't taken off the cylinder yet to de-varnish it, but as I was playing around with it, I could feel a stiff bump as it passes through BDC. I took off the backplate and it freed up, so I figured the crank pin was contacting it. There were no marks under the magnifying glass. I used some 800 grit paper to sand the backplate just enough to give it a uniform brushed finish, and re-tried it. The bump is still there but no marks at all. If I pull on the drive plate or push on the drive plate while I turn it, the bump is exactly the same. If I back the plate out quarter of a thread it all turns free, so something is definitely contacting the backplate. Upon closer inspection, the piston skirt at BDC is in close enough proximity to possibly touch the backplate.
Anyone ever had this?

**Cribbs74** Wed Jul 04, 2012 10:58 pm

Sounds strange Rusty,

It should have SPI. I wonder of someone reset the piston it may have taken the SPI away and in doing so shortened the piston/rod distance away from the backplate. Mark the top of the backplate and grind a little away and see if things clear up.

Also sometimes when ball/socket play is excessive you get that bump too when at BDC. Some of my engines do that but, runs fine. The .09 is no different than the .049 except for displacement so you should be able to figure it out.

Hope that helps.

Ron

**RknRusty** Wed Jul 04, 2012 11:11 pm

cribbs74 wrote:Sounds strange Rusty,

It should have SPI. I wonder of someone reset the piston it may have taken the SPI away and in doing so shortened the piston/rod distance away from the backplate. Mark the top of the backplate and grind a little away and see if things clear up.

Also sometimes when ball/socket play is excessive you get that bump too when at BDC. Some of my engines do that but, runs fine. The .09 is no different than the .049 except for displacement so you should be able to figure it out.

Hope that helps.

Ron

I'm familiar with that bump from lash between the pin and the crank, but this really feels like an obstruction.
So, are all Tee Dee .09s supposed to have SPI? Maybe that's a clue. I'll try to find the time to take it all apart tomorrow. Packing for the beach is at the top of the list though.

Jason_WI Wed Jul 04, 2012 11:20 pm

Sounds like the piston skirt is hitting the back of the rear cover. I had this happen to a TD 049 when I reset the piston that was pretty loose. I took some off the rear cover and problem went away.

microflitedude Wed Jul 04, 2012 11:34 pm

I thinks Jason is right. When I was over there I felt it.

John Goddard Wed Jul 04, 2012 11:58 pm

Non SPI to my mind Rusty, says TD09 R/C.
Or possibly a combination of standard and R/C
Parts Which perhaps aren't entirely happy
Together.
I think it's more likely to be a poor reset job
Though.
Has the cylinder got wrench flats milled?

**RknRusty** Thu Jul 05, 2012 1:48 am

John Goddard wrote:
Non SPI to my mind Rusty, says TD09 R/C.
Or possibly a combination of standard and R/C
Parts Which perhaps aren't entirely happy
Together.
I think it's more likely to be a poor reset job
Though.
Has the cylinder got wrench flats milled?

Whew, just got up to shake off a wild dream. Now I'm back to cox engines, that should clear my head.

I wondered if it might be a former RC engine. But either way only the cylinder would be different and the piston wouldn't normally hit the backplate. If I can determine that the cylinder is meant to have SPI, I'll shave the skirt. If not, I'll decide whether to do that or just take a little off the edge of the backplate. I don't know if it has wrench flats. I'll check that when I wake up for good. With the tight pinch I mentioned, if it isn't varnish, I may need to find a new piston.
Thanks for the replies.

Gotta fix my Mazda tomorrow too. I was jammin' some twistys and heard a Pop. Later there was oil under the car. Oh crap, that's never good. Turns out my fluid filled top motor mount exploded and made a big mess. It looks just like engine oil. I hate anything messy under the bonnet.

**Cribbs74** Thu Jul 05, 2012 5:11 am

Rusty,

All three of my .09's have SPI..... I am certain mine are non RC.

**Cribbs74** Thu Jul 05, 2012 6:19 am

Bonnet?

It's a Mazda not an MG Wink

**RknRusty** Thu Jul 05, 2012 7:08 am

cribbs74 wrote:Bonnet?

It's a Mazda not an MG

I was saying that so John would know which end of the car I was talking about. Smile

Now, about the .09; I took it apart and the piston is domed. And I'm pretty sure it's not a Mopar performance replacement.
lol!

So, mystery solved.

**Cribbs74** Thu Jul 05, 2012 7:11 am

Bummer

Sorry to hear that.

fit90 Thu Jul 05, 2012 7:14 am

Rusty,

PM sent

**RknRusty** Thu Jul 05, 2012 7:18 am

cribbs74 wrote:Bummer

Sorry to hear that.

It's okay, it was a gift, something to explore. I'd never seen one before. If I can get a replacement piston, it should be okay. The bearings are rough but not pitted, nothing to stop it from spinning.

66 Malibu Fri Jul 06, 2012 12:01 pm

Rusty,
Check the crankshaft for axial side to side play in that the case may be worn out.
Why I say that is, I once bought a bag full of B/W engine parts from a guy and quickly found that 5 or 6 of the cases had been totally worn out. I assembled the nicest ones and the crank would lock up solid at about 1/2 a turn on each one. What I figured out was that he had ground the engines to junk with an electric starter.From the looks of the junk, he only had three tools, an electric starter, a pair of vice grips, and a way to big screwdriver. I finally got 2 to run but it was a chore and the rest of the parts went into the junk box................Steve

RknRusty wrote:
cribbs74 wrote:Bummer

Sorry to hear that.
It's okay, it was a gift, something to explore. I'd never seen one before. If I can get a replacement piston, it should be okay. The bearings are rough but not pitted, nothing to stop it from spinning.

WingingIt74 Fri Jul 06, 2012 12:40 pm

does it have a copper gasket?

**RknRusty** Fri Jul 06, 2012 2:51 pm

66 Malibu wrote:Rusty, Check the crankshaft for axial side to side play in that the case may be worn out.

I'll take a look, didn't think of that.

WingingIt74 wrote:does it have a copper gasket?

It has copper head shims and a phenolic driveplate spacer.

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TD .09 - Something interfering with the rotating assembly

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