My engine was was not open for many years and runs well. Oil pressure is good, from 2.5 to 4 BAR, but engine is a bit noisy. No, it does not nocks, but I'm not sure, that my bearings are ok. Were not replaced for more then 400k.

The quation is what to do - replace them with original ones ore get oversized to 0.25 mm and repolish crankshaft? I dont want to drop the oilpan when new bearings are not bought.

 

hot idle oil pressure is the most telling sign of worn rod bearings, below 10 psi on most Fords
will also see an increase in oil consumption as more oil sprays out of loose rod bearings onto piston rings and cyl walls
usually caused by plugged oil pickup screen from lack of regular oil changes, poor quality oil or worn out oil pump

rod knock shows up usually on light load accelerations up hills and onto uphill freeway onramps

400k km is not high rod bearing mileage for a 3L Aero
but Pablo, your engine is overbore and high compression and sees high speed racing runs down the track

the rod journals on these engines seldom wear enough to have to machine except when there are oiling problems and bearing failure meltdown with grooving heat damage to micro machined journals

your noise is probably the poorly oiled rocker arm assemblys, they wear and are loose at 100k miles on many rigs...push rod tips collapse, rocker arm tip holes wear out and thru....same problem old Ford Y blocks had

shop here in Washington St. rebuilds the 3 and 4L rocker assemblys...hardened chrome moly push rods and rocker arms with induction hardened tip holes
if you have access to slightly longer chrome moly push rods and an induction hardening machine, can make your own tough push rods and rocker arms

can also weld up rocker arm holes with hard surfacing rod and remachine hole with carbide or diamond bits

my 4L has had a noisy rocker, pushrod, lifter on cold startup since it rolled off the assembly line...tried different oils, nyet-nada
so used to it now, don't hear the rattle

 

Well. When my van is on lifter and I can run engine and be under the engine, I hear noise somvere in oil pan area inside the engine. There was no this noise before. And my odo is in miles, not KM. So my engine was not rebuild for 400 K miles. When I pushed my engine to I replaced main bearings only. Krankshaft was ok, but bearings were worn.

Oil pressure is always ok, becouse I have perfomance oil pump.

 

400,000 miles....I would drop pan and check bearings

cam chain/gears?

when you changed main bearings, what was the condition of the thrust bearing section....any extra wear from the clutch?

do you have access to a product similar to Plastigage? made by Clevite which is now part of Mahle and should be available in EU.
http://www.clevite.com/techbulletins/CL77-1-205R.pdf

let us know what you find when you drop the pan this summer in warm weather, Pablo

 

The oil pan on my 2 wd 4.0 drops in 20 minutes, much blood but 20 minutes. Rod bearings shot at 160000 miles, mains perfect. Completely down through 3 layers of metal, down to the steel. Rod bearings lead a tough life. Poor oiling and big centrifugal loads. New rod bearings are 28 bucks in USA. If your pan drops easily, turning the crank counterweights helps, maybe worth the expense.

Ken

 

Rod bearings should last the life of the engine, but they are the most vulnerable, since they are subjected to the most stress. IF something is amiss in the lubrication system the rod bearings will take the brunt of it. I would say to stick with OEM spec bearings, no point in changing the size.

 

Basically an inspection of the Big end shells will tell you if they are worn. The crankshaft is not so easily inspected without measuring . If you know the specs you can measure with micrometer. If not then use the compressed plastic method (plastigauge). If crank journals are oval or worn get crank ground or replace crank.

If no rumbling present mains should be O.K.
When this job is undertaken is when you wished that synthetic oil & new oil pump had been fitted previously!

Aeroman

 

Well. What may happen if I replace old bearings with new, but original size, but crankshaft is worn. How long life of new bearings may be?

 

If crankshaft is out of tolerance, new shells will wear out again much quicker than normal. If crankshaft is good, your engine will sound sweeter & oil pressure may increase a few PSI. Infact the bottom end may sound like new again!

I dont know your garage set-up, but it would be worth getting the crank measured, just to be sure, but if not then new shells cant hurt anything & if they go again within, say 6 months , you know the crank was bad (it is possible to get sludge blockage in the oilways). If the shells are worn through the soft metal to the backing anywhere on the bearing surface, 90% chance the crank needs to be ground.


Good luck Aeroman.

 

Ok! I will drop the oil pan and see sheels before odering bearings. I have 1 more crankshaft and I can rround it and replace my later with bearings.