Broken pushrod

[John McCormack]

Last Wednesday I was driving my TR3 (DTR9602O, an early small mouth) to a club coffee. After going through traffic onto the freeway and then cruising down it for about 25 minutes at 110-115kmh, I took the exit and the car started running on 3 cylinders. I thought straight away a burnt valve, although it sounded a more than a small chip in a valve.

No strange noises from the engine so I pulled over to check simple things like plugs etc. All in order so I continued to the coffee just a few minutes further down the road.

Did a more thorough check there and was confident it was a valve problem. Oil pressure, oil, coolant, etc were all good.

When I pulled it all apart at home this is what I found. I've not heard of or experienced a broken pushrod in a roadgoing TR before this one. This car was raced and put on a dragstrip in the 50s and 60s but nothing strenuous since. After this work it sat in a garage for nigh on 35 years only being serviced and driven for an annual inspection. I got it two years ago and have been using it quite regularly and drove it to our last nationals in October, about 2200kms round trip. I suppose I've done 3,000ms in it.

There was no other damage (luckily) so I've ordered all the bits I need and it should be back on the road by weeks end.

[Motorsport Mickey]

The page isn't found John. Check your loading of it.

Mick Richards

[BlueTR3A-5EKT]

Original push rods?

Solid or tubular push rods?   
 

Solids were replaced on TR2 because of weakness.  
 

Steel or aluminium pedestals?   The steel ones crack 

[harrytr5]

Had this on a TR6 and turned out to be a jammed cam follower. Engine not turned in years.

Regards Harry

[John McCormack]

1 hour ago, Motorsport Mickey said:

The page isn't found John. Check your loading of it.

Mick Richards

Here it is. Just a photo of what I pulled out.

[John McCormack]

31 minutes ago, BlueTR3A-5EKT said:

Original push rods?

Solid or tubular push rods?   
 

Solids were replaced on TR2 because of weakness.  
 

Steel or aluminium pedestals?   The steel ones crack 

The pushrods are tubular but I believe they have been in the engine for many decades. The previous owner bought the car in 1958 from the original owner so I have a complete history. He cannot remember changing them so could they be the original ones?

They are steel pedestals, all in good condition.

I suspect the pushrod was bent in its racing days and I never thought to check them. 

[james christie]

Take care when ordering the replacement(s). You say the car has done some competition work. Has the ‘head been so skimmed that the push rods have been shortened?

I recently had to return a set of new pushrods to Moss as the ‘head has been so modified and my tubular pushrods so shortened that the solid replacements left no room for the adjustment of the rockers.

james

[john.r.davies]

It must be the season! 

Three weeks ago,  at Donington,  my TR6 engined Vitesse suddenly acquired a tapping noise on the green flag lap of the race.  I withdrew, and found that one OE push rod had bent, pushing it's neighbour off the rocker.    One was jumping up and tapping the cover ever second rev.
 

Thank you, Revingtons, who supplied a set of shorter tubular rods in double quick time, so I'm out at Oulton this weekend, in the CSCC Swinging '60s.     I was late to enter because of this, so am third reserve, but I will get a practise and if the normal attrition is a little more, a race!

JOhn

[John McCormack]

12 hours ago, james christie said:

Take care when ordering the replacement(s). You say the car has done some competition work. Has the ‘head been so skimmed that the push rods have been shortened?

I recently had to return a set of new pushrods to Moss as the ‘head has been so modified and my tubular pushrods so shortened that the solid replacements left no room for the adjustment of the rockers.

james

The head is only .0085" down from original. He did supercharge it at one stage.

 

[BlueTR3A-5EKT]

Image I posted before of cracks in the ferrous rocker shaft pedestals of a TR2.  Later cars used cast aluminium pedestals.

The cracks are visible inside and on the end faces.

Such cracking is unlikely to have caused your push rod failure though.   Worth inspecting if it is all in bits.

 

Edited April 25 by BlueTR3A-5EKT

[John McCormack]

All back together and the car is driving superbly. The engine is a lot quieter than it was, further evidence that the pushrod was probably bent before and I didn't pick it up.