Most miles on a pushrod Jaguar in 2024

Hi all,

Well, I am a bit pathetic regarding this. I was supposed to run to a club meeting on Monday with the MKV but there was very heavy rain, so I took the V12 E as it has a waterproof (factory original) hood. (aka. top)

Sooooo, so far this year I have done 100kms = 62 miles. :slight_smile:

But there is good and bad, the bad is that my water pump outer bearing is shot, again. Ok not a difficult job, but still frustrating. The good is that my steering has never been this good in my 22 years of stewardship! :smiley: No free play anymore, and no jamming and not at all heavy IMHO when parking with the skinny 16" Cinturatos.

Cheers!

PS. I did over 3000kms in May with the 456 GT, to Monaco for the Grand Prix Historique, it was awesome, and visited the fantastic Motor museum in Turin, Italy on the way, as well as the Emil Frey museum in Safenwil, near Basel, Switzerland. My favorite three cars in the countryside now:



Three cars, thirty cylinders and five decades!

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Well, I will attempt to surpass that this coming Sunday in my '38 SS, 82 miles to the Michiana Brits all-British Car Show at Notre Dame in South Bend. Hopefully 82 trouble-free miles back, and with the summer solstice it should be before dark.

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I wish you all the best, Rob. On Tuesday night I got back here at 12:00 in the middle of the night with the V12 E. It was not dark. :slight_smile:

Cheers!

Hi,

Yesterday was nice, summer solistice and I was able to almost double my mileage, 61 miles yesterday, so a total of 123 miles this summer. :slight_smile:

And I reached a couple of milestones, 1st time since the engine rebuild I hit 70 mph and passed the total of 6.000 miles under my stewardship! :smiley:

Cheers!


Nice looking car Pekka
I am hoping to do some mileage in my MKIV before the summer finishes, I have been restoring it for the past 3 years and have not started the engine yet, don’t even know what they sound like, never mind how they drive!
Mike

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Hi Pekka, way cool to see the big “70” on your speedometer!

Now here is my usual cautionary note. I generally don’t run my engine over 2,500 rpm very long. Southern California freeways run at about 80 mph when not near absolute halt. When I am on the freeway for short distances, I will bump the speed up to 55 mph and for sure not over 3,000 rpm. I keep this modest rpm level since I know the forces on rotating engine elements go roughly as the square of the rpm and I don’t want to open the engine up again for repair.

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I agree with Roger on the exponential rise of forces and when I was running on Dural conrods I too regarded 3000 rpm as my rev limit but when I fitted steel rods I allowed myself a bit more leeway for occasional bursts of speed.

image

Peter

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Fair point, I agree for anyone still with 70+ year old Duraluminium con rods. But as I have steel con rods and everything balanced very carefully I think that certain higher revs should be fine. Also the 3 1/2 Litre has the crank vibration damper, not that I would think a good inline six necessarily needs it.

Just like in the XK engines I try to avoid running long periods at 2.400, 3.000, 3.600 or 4.200 rpm and rather run at 2.700 or 3.300 rpm. Of course Your Mileage May Vary. :wink:

Cheers!

This talk of the alloy con rods is making me nervous as I have not opened my 2.5 engine up at all, this is due to Peter Scott and the previous owner opening it up and replacing big end shells and piston rings etc so I have not felt a need to

I had already set myself a max speed of 50-60 MPH for when I get my car on the road, and 3000RPM max sounds sensible to me however is there some historical data to justify the cautionary tales of the inferiority of the alloy con rods verses the steel ones ?

Mike

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All the data I have seen reported over the years on aluminum alloy conrod failure in the pushrod engines is anecdotal. Yes, there have been some failures reported. On the other hand, I replaced my aluminum conrods on my daily driver when it had about 115,000 miles on the engine. In the maybe ten pushrod engines I have worked on with my hands, I’ve never seen an aluminum conrod failure. If anyone out there has photographs, I would love to see the fracture pattern and stress riser wear symptoms on a failed aluminum conrod. I used to enjoy reading the patterns on Willys jeep rear axle shaft breakages, which occurred with high enough frequency I carried spare axles on long offroad excursions.

It is pretty easy to change the conrods if an engine rebuild is in process. It also is pretty easy to see if aluminum conrods are present in an engine if the oil pan is off.

I have seen, my anecdotal observations, that poor oil and coolant maintenance on pushrod engines has led to a lot of cars being parked. Cracked blocks, ruined valve guides, flow-blocked rocker wear are pretty common in my experience.

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I think your car does have Dural rods.
image
That said, there were at least three different versions of Dural rods. The earliest were very elegant and the subsequent rods became progressively more chunky and less elegant. Your car is a fairly late model and will have the most inelegant rods.
I drove my car for 20 years on Dural rods but I did set myself a rev limit of 3500 rpm and I always changed down rather than let the engine labour.

Peter

Thanks that’s reassuring

Sooooo, I haven’t been doing any miles lately, as I got hit again by the ”Oil Pump Shaft Blues”. :frowning:

I was going to do some shopping with a relative car nut friend amd only got about 1.5 miles from the cottage before oil pressure dropped to zero. :frowning:

So, I tried again to fix it on the roadside, but nope, it would idle 1-2 mins with good oil pressure and then the shaft would jump and pressure drop to zero. So we limped home one minute at a time only driving when the pressure was good.

That was a couple of weeks ago. Today I took out the air silencer, the carbs, the generator, the distributor and finally the tappet cover and I was able to fit one 1/2” snap ring I had received from Rob @Rob_Reilly a couple of years ago. More to follow. I will also replace the water pump front bearing, again.

Cheers!

Ps. Some pics:





Th’ best laid plans o’ mice an’ men ere aft gang aglee. - Robert Burns

Car was all ready to go. I never even started the trip. The Lord had other plans for me. Friday morning it felt like an elephant was standing on my chest. Drove to Franciscan Hospital. Diagnosis is aortic aneurysm with dissection, emergency helicopter ride to Northwestern Memorial Hospital in Chicago, successful aorta repair, then 20 days in hospital recovering. First day home now, still very tired and weak. It’s taken me all day to compose this response. No driving, guitar playing or heavy lifting until end of July. Relatives and friends are taking care of me.

I have a theory about the aluminum con rods, unfortunately impossible to investigate at this late stage.
Wrong or mismatched bearing shells.
First AL con rod had an OFFSET steel oil tube.

Second AL con rod had a CENTER DRILLED oil passage.

Note offset vs center drilled oil hole.

C2844 aluminum con rod with C1144 bearing

The oil holes should be aligned to get the best oil flow.

Rod bearing replacement used to be fairly common with major overhauls.

My theory is that people rebuilding these engines back in the '50s used the wrong replacement shells, and thus the wrist pins in the pistons were to some extent oil starved, especially at the higher speeds common on US highways. Friction at the wrist pin would lead to bending fatigue a bit lower down in the rod shank, and eventual failure in the rod.

Impossible to know now if there is anything in this theory, though if anyone had a wrecked con rod I would love to see it.

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Hi,

Glad you are ok and wishing for a smooth and successful recovery. :smiley: :+1:

Cheers!

Hi Rob,

I’m sorry to hear of your medical emergency and hope you make a full recovery in time for your Scotland/Ireland trip.

Best wishes,

Peter

HI Rob

Hope you have a quick recovery and its all behind you

Best wishes
Mike

Thanks friends.
Scotland/Ireland tour is still on. Looking forward to meeting Peter in person and seeing his SS. Hope I’m able to crawl under it. As I recall, Peter was instrumental in helping me get my brakes sorted out. They were assembled all wrong by some previous owner. Not quite the same as post-war cars.

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Rob just read this from my end: I wish you a succesful recovery too. Take care.

Hi all,

Finally back on the road, only about ten miles yesterday, but good oil pressure and no noise from rattling bearings anymore.

Now I just need to set the ignition timing again and adjust the SU’s, again. :+1:

Cheers!

Ps. Darn iPad, it thinks I’m downunder! :laughing: