59a Engine Failed Big Time.
 

Have a 46 Merc Coupe which had a "rebuilt" engine in it but used about 0.5 litre of oil per 50 mls. Brought another engine off our local ebay called Trade Me.
Standard 3 3/16 bore.New rings, new cam shaft brgs, New heads NOS never been on an engine. runs at 70 lbs oil pressure at start up then 60lbs.

Swapped this into the car and immediately noted low oil pressure when warm around 10lbs. Went to a heavier oil 30/70 and some improvement 15lbs when warm at 50 mph. Did some short low load runs to get some miles on engine.
Couple of weeks ago went to a car show but didnt quite make it home.
A clatter and bang at 50mph cruising. Kept going to get off motor way to find safe spot to stop. On stopping oil/water mix spewing from road draft tube.
Got car towed home by a helpful passing driver.
The mess on removing engine:
Hole punched through both sides of oil pan. Cam shaft broken aft of No 2 & No6
shaft broken into quite small bits. Gallery area support areas for valve guides 7 back to 8 smashed up. Piston rod No8 broken.Ah this explains holes in oil pan. Rod was gone and only bottom end brg almost flush and same at bottom of No 8 piston. No 8 piston lower skirt broken off, No8 liner scored,
Plenty of broken bits in oil pan. Nil siezed brgs. Pulled No8 bottom end brg and No4 piston. Both bottom end brgs through to copper.
No 7 piston shows a contact ring mirrored in head.These heads had previously never been used NOS.
Block is history and c/shaft shows signs of external damage caused by flying bits prior to stop.
Hard to tell what came first, No8 con rod or camshaft.
Let the buyer be aware. So now to test the sellers good will as only had 180 easy miles racked up on this " inspected part rebuilt" engine.
Ideas and thoughts would be appreciated.
Phil NZ

Re: 59a Engine Failed Big Time.
 

The rod would have gone first and took the cam out when it started flailing about. Had it happen to a 390 Fe motor ages ago. Piston turned in the bore and took the cylinder out. It sounds like a similar failure to yours.

Hard luck though. Any rattles or signs that in retrospect could have been taken as a warning?

Mart.

Re: 59a Engine Failed Big Time.
 

No prewarning signs as such. Just the concern on low oil pressure but nothing had picked up in the bearing area. The loss of the bearing surface through to copper at bottom end bearings I suspect may have been there from the outset.
Appreciate your input. Have the original engine out and stripped for a rebuild.
Phil NZ

Re: 59a Engine Failed Big Time.
 

Phil check to see if gudeon bushing is seized on broken rod. Rods don’t just break at that rpm. Low oil pressure contributed some how I would believe. We’re rod nuts tight

Re: 59a Engine Failed Big Time.
 

Cams don't beak unless hit by something HARD!! Probably the broken rod. Problem was caused by a lubrication failure.

Re: 59a Engine Failed Big Time.
 

On the rod that broke, is the big-end still on the crank? Or is it all gone as well? My guess is that either the big-end seized on the crank (due to lack of oil pressure), or the cap came loose and the rod turned everything into a blender. What type of crank in the engine? Was it is Merc crank?

Re: 59a Engine Failed Big Time.
 

15 lbs at 50 is not enough. You need 10 lbs for every 1000 rpm to be safe.

Re: 59a Engine Failed Big Time.
 

Sorry to hear that Phil,
Would the low oil pressure along with the failure denote a restricted oil galley or crank oil passage? .......maybe oil pump restriction?
I have pulled several “good” v8 and 4cyl engines down to find hard sludge in the pan and galleys. Impossible to tell without positive inspection.

Re: 59a Engine Failed Big Time.
 

I would check two things. First, make sure the plug is in tight at the front of the oil galley, behind the cam gear. When they come out, most of the oil goes there. Then, check the gears behind the cover at the rear of the cam. A problem there will cause low OP. This won't fix your engine, but may help tell what happened.

Re: 59a Engine Failed Big Time.
 

Gudeon pin bushing is still free moving on pin. The rod nuts were tight.
Phil NZ

Re: 59a Engine Failed Big Time.
 

Ron thanks for your input much appreciated. My feeling is I did not contribute to this " screw up Breakdown". Nice to learn from this and move forward.
Phil NZ

Re: 59a Engine Failed Big Time.
 

Big end was still on crank, free moving and nuts tight and secure. On removal noted bearing surface through to copper surface.
Phil NZ

Re: 59a Engine Failed Big Time.
 

Yes thats the reason I went to a heavier oil grade. The 70 lb on start up fine till oil warmed up! Too much clearance at bearings?
Phil NZ

Re: 59a Engine Failed Big Time.
 

This engine was "rebuilt?? " however a reasonable amount of sludge in oil gallery. removed Oil pan for inspection prior start up on stand and simiar .
Phil NZ

Re: 59a Engine Failed Big Time.
 

Appreciate your advice and will check these areas.
Phil NZ

Re: 59a Engine Failed Big Time.
 

Have rechecked pistons and heads. There is noted contact circular mark on pistons No7 and No8 these contact areas are noted at same areas on heads. These heads were NOS never been on an engine.
Removed head gaskets, copper type measured 55 thou .
Phil NZ

Re: 59a Engine Failed Big Time.
 

Since you have piston to head contact and rod failure maybe the rods had a tough previous life....
Sudden drop in oilpressure...spring in relief valve in liftergallery broke ?...or something got in there keeping it open.
How far up is the pistons going ?...above the deck ?...with uncut heads there should be plenty of room between heads and pistons...

Re: 59a Engine Failed Big Time.
 

Just because it is nos doesn't mean it is good, some nos parts stayed on the shelf because they didn't fit properly
A broken rod will stitch out a cam and the block
Since 7 was hitting try the other head and foil balls, clay and see it both heads have same clearance
What condition are the cam bearings--- a cam bearing failure could cause the oil pressure loss, and the cam loosing support of the bearing could break
A very loose rod bearing can let the pistons hit the head, but with floaters most likely it would be the pair on that journal---4-8
If the same guy did both engines find someone else for the next

Re: 59a Engine Failed Big Time.
 

Same guy did not do both engines. The cam bearings were reported replaced new ones..Will check both heads for clearance. The rod bearing nuts were tight but as stated rod bearings through to copper.
I suspected too much bearing clearance to be to cause low low oil pressure when warm.I had checked the relief and spring in oil gallery and all was ok.
The rod letting go seems to be the start of the problem then the cam as you say.
I'm wanting not to pull too much more off as may need to get an independant assessor to view to help support my claim with seller.
I really appreciate all the useful comments with this screw up.
Phil NZ

Re: 59a Engine Failed Big Time.
 

Measure the cam and new cam bearings, also.
I had a reputable supplier send me a cam with reground journals
with standard size bearings.
He did make good, promptly.

Karl