Catastrophic oil pump failure

[westaus29]

Last September we went on a three day rally with local club members to Collie, a coal mining town in the hills south of Perth WA, about 100 km from home, driving our trusty 29 Plymouth tourer. On the second day we had just finished a circuit round the local speedway track, headed off back to town at 35 mph, checked oil pressure fine at 40 psi, then all of a sudden bang and clatter, clutch in and coasted to halt, engine still running, no oil pressure. No sign of external damage at first, due to bright sun and black engine block, but eventually saw oil where it should not be on outside of block, felt a jagged crack, oh b@#$%^. Local member stopped, we explained problem, and off he went for trailer. So we had lunch on side of road, took Plymouth 100 km back home behind a struggling Valiant 6, DROVE the Plymouth into the shed, then came back in time for dinner celebrations.

It wasnt a good time for this to happen as I had just started stripping Jill's 7 passenger 38 Plymouth for body-off restoration. It is hard to believe how many parts came off it! I have a 5 car bay shed and in desperation had to install a mezzanine floor down one end for the extra bits like seats, windows and running boards. For various reasons the sand blasting of the 38 body and chassis took till Christmas so have only now started on the poor 29.

Basically what happened to the 29 was that the oil pump shaft sheared just below the vanes. The shaft and gear then dropped into the sump and bounced around for a while, knocking a few cracks in the block here and there, in the process bending a rod and punching one bolt 1 cm thru the big end so that the nut was more than loose, and gouging holes in the crank. The camshaft had a few chunks taken out, the gear was damaged and the shaft was bent. The oil pump body was also split. What a mess. I suspect the crack may have been developing for some time, as had been getting some occasional loud noises from oil pump at startup and kept meaning to pull it out and have a look. A warning for you all!

Luckily I have a few spare blocks, so picked one with similar engine number and send it down for cleaning and checking. It looked ok and was 20 thou oversize so ordered new 40 thou pistons and rings from Egge at their Christmas special price. Next was the crank. My best spare crank was too worn so chose to try and recover the original. It didnt appear to be bent, so have cleaned up dings and carefully dressed down a few spots where big end side faces were bulging slightly due to hammering they took. The crank has now gone for crack testing and balancing, together with flywheel and pressure plate, a job I couldnt afford back in 1999 when still had kids at uni. Pistons have arrived and block is being bored. A selection of valves is being refaced. By the way, the exhaust valves were badly pitted. I am going to make sure I use Flashlube additive regularly in future. Luckily I have a spare camshaft in decent shape so dont have to fix the old one.

So now it is back to the 38. First job is to make some stands for the very large and heavy chassis. On the way to sand-blasters we were stopped by police. "What are you doing with a truck chassis on a car trailer" they asked - the back wheels were hanging offf the rear of the trailer - must try and find a 7 passenger trailer!

I have attached a few pics, I hope, as first attempt at this.

The car with bonnet half removed - much easier to take side panels off first, less risk of damage.

The oil pump before removal - no sign of what lies behind

The bent crank and bits of the oil pump

The damaged big end bolt

The damaged pump body

I'll try and add the rest to a second post, suspect I am not doing this right

Where the shaft sheared

Hole 1 outside block

Hole 1 inside

Hole 2 inside

Hole 3 outside

[westaus29]

A few more pics

Where the shaft sheared

Hole 1 outside block

Hole 2 inside

Hole 3 outside

I guess an expert could repair the cracks, and I am not throwing the block away as am pretty sure it is the original and is standard bore.

The rest of the motor was in good shape meaning that the reconditioner in 1999 (me) did a reasonable job.

[frankp]

My goodness!!  Thanks for the warning to check out any strange noises.  Good luck to you with both the 38 and 29 projects going at same time- whew!  frank

[Old Man]

I'm not a professional on metal fatigue but I think the shaft has been cracked for many a moon. The 'smooth' part of the crack is when it let go. The 'pebble' finish part is a very old crack. I suspect the noise you heard was the shaft being out of round. It must of started to wobble but only for a few klicks before it snapped. End shaft pressure must have kept it intact until some transient high torsional load snapped it. Thanks for sharing this with us. 

[aussieQ]

Hi Westaus29,
Sorry to hear about your pump failure. These things seem to happen at the worst possible time. Lucky you had a spare engine block to rebuild.
A good warning to us all to keep on top of any unusual noises.

Regards

Gary S

[imoore]

Sorry to hear about that. That is something would never had thought could happen. But what a mess.
I wonder if at some point in the engines life it has run low on oil causeing the pump to half sieze. Then as time goes on it eventully decided to let go.

Ian.
Btw nice car.

[chetbrz]

Sorry to hear about your misfortune.  You mentioned 40 psi pressure.  That might be a little high for these engines my assumption was that 40 psi with the old gauge ?  I think there was a discussion on this web someplace about oil pressure.  I know on my 48 there is a pressure relief valve.  I don't remember off hand but suspect the same on the 4 cylinder.  Might be something to look into.

Anyway sorry to hear about your misfortune. 

Chet...

[westaus29]

I agree that the fracture pics indicate that the crack was there for a while. Too many things on the go, I guess

Re oil pressure, the manual says 35-40 psi is normal .. I was reading the dash gauge, not sure if accurate. A mate's 1927 4 cyl Chrysler has similar pump and similar operating pressure to mine. Most other cars of that era run much lower pressure, which maybe says something about Chrysler engineering, except the 27 model still has the Maxwell engine. The 4 cyl Plymouth does have an adjustable oil pressure relief valve but I cant remember how I set it up originally in 1999, suspect I cleaned the black treacle out then put it back to original number of turns.

Jim

[SDGlenn]

Sure enough sorry about your misfortune. Some times life is a B***h.  Thanks for the insight, my 29 has had a slight rattle I haven't found, this may be a reminder to get mine taken apart before the same happens to me. I have had the pan off, checked all the mains and rod brgs, and anything else I could see, looking up, with oil dripping in my face. I have put on quite a few miles, but trying not to push very hard, just keeping my fingers crossed and praying a lot.  (but it runs so nice) Thanks again. Beautiful car.....
SDGlenn

[Tinkeys]

What's the latest on your engine hope it's all good !
I did put your brake fluid canister to good use it's on the car !
Thanks again !
Cheers Tony.

[westaus29]

Hi Tony,
Good to hear you've tried out the new brake fluid reservoir .. I've seen lots of variations on 29 Plymouths, including a glass container with French logo.
My block is still at reconditioner's being rebored and valves faced. I havent chased it up as have been busy cutting rust out of my 38 Plymouth and helping a mate with 29 Buick spring bushes. I much prefer Chrysler engineering, they stick to standard sizes, simple design.
I have been keeping an interested eye on your 34 Dodge rebuild. You are sure game to try anything, and a real fast worker! Dont neglect the old Plymouth tho .. there arent too many of your model over here.
I am coming over to Melbourne in March to vist mum and may give you a call.
All the best Jim

[Tinkeys]

Would like to see you again ! starting my holidays today for 3 weeks going to do some fishing and caravaning around NSW will be back around 15 March !