View Full Version : TR2/3/3A clanking sound at idle on TR3

10-14-2012, 06:29 AM
Car idles around 700 rpm's. Slightly rough idle but acceptable. I get a clanking rattle with no particular rhythm at idle. ( take two box wrenches and hit them together ) metal to metal clank. If I increase the idle speed it goes away. I have driven the car now, several times and it runs very well on the road and has actually been "pushed" spiritedly a few times. No strange noises under driving conditions. The sound seems to come from under the engine. Should I suspect anything in the crank,pistons,rod bearing area, or just keep looking for something loose? Sound does not change when clutch depressed. Had transmission out and replaced clutch. T/O bearing was OK. I have reached around under and around the engine trying to find something loose but nothing found. Any suggestions for diagnosis?

10-14-2012, 06:32 AM
Quick addition: I have placed long screw driver on head, block,water pump,timing chain cover, generator and listened through that. No strange noise other than the sewing machine sound.

10-14-2012, 07:00 AM
If the spring steel timing chain tensioner fails, it often makes a noise like this.the outer shell fractures off and is just banging about inside the cover making an irregular tinking sound. This is a precursor to a total failure as the chain will soon jump time,and the bits of steel in the oil domajor damage to the front main bearing.....
MD(mad dog)

10-14-2012, 07:01 AM
Sounds somewhat similar to what I had when the front hub was coming loose on the crankshaft.

I had removed the fan and extension (to make room for an electric puller) and installed a shorter bolt & big flat washer to clamp the hub in place. But the washer pulled up against the end of the crankshaft with the hub only partially clamped, so the hub eventually started to work back and forth. Timing chain tensioner was broken too but I think the hub was making the noise.

Anyway, just a thought for something to look at.

10-14-2012, 07:35 AM
My front bumper brackets (the roundchrome tubes) used to rub against the holes in the grille and make a squeek only at idle that I was sure was the water pump pulley rubbing.

So look around outside of the immediate engine as well.

10-14-2012, 07:43 AM
If you still have the old metal fan, check that the rubber mounts are still good. If they are deteriorated it could let the fan move and you may get a clanking sound.

10-14-2012, 09:50 AM
Does the rough running also cause the engine to bounce around? If so, I'd also check out the exhaust system.

10-14-2012, 11:58 AM
I had the woodruff key on the water pump pulley wear, allowing the pulley to hit the WP mounting nuts causing a similar sound. with engine not running, see the the pulley rocks on the shaft. also, maybe check the generator attachment bolts and mounts.

10-14-2012, 03:28 PM
Some great ideas so far, especially since no one has indicated they thought the main, or rod bearings were suspects. I initially thought of the timing chain, but wouldn't my "crude" mechanics stethoscope have picked up that additional noise when held on the timing cover? Could be wishful thinking on my part, due to not wanting to remove my freshly painted front nose from my freshly painted fenders. I'll check the fan and pulley. I recently replaced the generator mounts and had the front plate of the generator welded up for the bolt hole being worn through.. I thought that was the problem, but the repair didn't stop the noise. Thanks for all the input,it helps me keep eleminating things as I run out of ideas.

10-14-2012, 03:45 PM
This is a wild idea but I've heard the pistons in the Strongberg carbs smack up and down if they were dry inside (no oil). I don't know if the SUs could do the same thing.

10-14-2012, 04:02 PM
Being down low, it could be a crankshaft thrust washer failed.

Or perhaps too much camshaft end float allowing back and forth movement. (tolerance 0.003" to 0.0075") Don't worry too much if it's the cam as they can clunk away for years without trouble.


Addition - strangely a wide fanbelt cracked on the narrow side can make a terrible mechanical noise at idle. First time I heard it I thought I had a broken chain tensioner.

10-14-2012, 04:28 PM
Appears the fan is the culprit. I can rock the fan on the hub and produce a noise. Good new/bad news in that I still have to disassemble my freshly painted body panel. It seems I need the rubber bushings and sleeves in the fan blade assy. I still like that much better than timing chains and bearings, just have to inlist some assistance in removing the front panel to avoid catastrophe to new paint. Falls under the catagory of, I should have done that while I was in there. Thanks again for the input. I'll start on that project on another day,just enjoying looking at the car right now.

10-14-2012, 04:46 PM
Appears the fan is the culprit. I can rock the fan on the hub and produce a noise..
Original fan, or the TR6 fan?

10-14-2012, 06:43 PM
Not sure how much clearance you have between radiator and the lower front apron - but I'd check if I were you to see if you can avoid pulling the apron. Removing the radiator guard and the lower radiator mounting bolts may give you just enough room to pull the old fan.

10-15-2012, 06:22 AM
Have the original fan. Appears the rubber bushings have dry rotted and allows the fan to rock back and forth on the bolts. Thinking of looking into the plastic fan though.
Randy, I thought about checking from under the car to see if maybe it could be done from there,but probably still would have no knuckles left,after working that close to radiator.. I think the crank bolt has to come out and it is pretty long. Haynes manual has to remove apron. I'm thinking about waiting and getting a new radiator at the same time and do it all at once.

10-15-2012, 12:22 PM
I think the crank bolt has to come out and it is pretty long.
Normal assembly order is to install the long crank bolt first. The fan assembly actually includes a lock plate to hold the long bolt from turning. So you don't need to remove that bolt to replace the fan bushings.

However, I agree, pull the apron. Even if you take the radiator loose on its mounts and move it as far forward as possible, there still isn't really enough to put things back together properly.

The good news is that, if the bolts aren't rusty, it only takes an hour or so of steady work to remove the apron. You should be able to complete the entire project in an afternoon.

The hardest part is what to do with the apron once it is off. When I did this a few years ago (before converting to an electric fan), I foolishly left it balanced on one side. A gust of wind blew it over and banged up the paint around the grille.

Don Elliott
10-16-2012, 06:40 PM
I had a rattling sound in my 1958 TR3A in 2003. It sounded like about 10 tea spoons in a tin cup being shaken.

It was intermittent and only ever happened at idle. It was the starter where the small drive pinion gear was not completely retracting from the teeth around the flywheeel. I pulled out carb #2, then the starter and re-built the starter. After that - no more rattling.

10-18-2012, 10:46 AM
Funny...or not so much...you should mention that. See my latest post regarding starter issue. I'm sure I have a rattling fan, but my have been some in the starter too.