Engine Bearing failure - Sprint?

[iandollysprint]

Looks like my engine has expired.

Trundeling along at a nice 60 mph and suddenly clank,clank,clank from the bottom end. Big loss in power, pulled over and got recovered to home.

Noise is a heavy knocking particularly under load.

I have since whipped the sump off and had out all the mains and big ends. Noticeable wear and tear but nothing that suggest "ah thats the one". Significant vibration is present even at idle.

Spark plugs all OK apart from No1 which is black (oil deposits maybe).

From underneath all the bores look OK, pistons move up and down OK.

From what I can see all valves are there but I can't check the inlets with them being bucket over shim.

I have a new set of big ends and mains to fit this week together with a new oil pump. I will then carry out a compression test before firing her up again.

No metal found in the sump or filter, carnk surfaces show some minor scoring but nothing terminal.

Question is how far gone does a bearing have to be for it to give loud knocking noises?

Anyone else experience a similar event?

Any advise/expereince would be appreciated.

Thanks

Ian
65k miles sprint on bricks in the garage.

[USASPRINTMAN]

Ian:

It might be the thrust washers... have you checked them?

Richard Truett

[iandollysprint]

Ian:

It might be the thrust washers... have you checked them?

Richard Truett

Yes. In place and OK. Thanks for the suggestion
Ian

[USASPRINTMAN]

The first sprint engine I had made funny noises from the bottom. I found that the bearings were the awful glacier or county brand and they were a bad fit in the big ends.
I replaced them with vandervells and never had another problem. It is possible to change the big ends and mains with the engine/crank in the car. doing so will result in several sore muscles, but not as many as yanking out the engine.

Richard

[Mad Mart]

It is possible to change the big ends and mains with the engine/crank in the car.

Yep, that's how I did mine last time.

[Jon Tilson]

A run big end with heavy clanking as you describe will be totally obvioius from the bearing shell and the damaged journal. If you have no such damage then mic the journals for ovality and put it back together.

The problem is probably in the top end....like a disintegrating rocker and cam lobe being the primary suspects.

Jonners

[iandollysprint]

A run big end with heavy clanking as you describe will be totally obvioius from the bearing shell and the damaged journal. If you have no such damage then mic the journals for ovality and put it back together.

The problem is probably in the top end....like a disintegrating rocker and cam lobe being the primary suspects.

Jonners

Not obvious from the bearings that have been removed. Only one big end shows sign of unusual wear. The bearing material has been depelated on the side of the bearing but only part way around.

My concern was the loss of power when it happened.

I'll run a compression check after fitting new big ends, mains and oil pump.

Thanks for the input

Ian

[iandollysprint]

Finally got the the bottom of my engine knock. Compression test reveals NO (zero, nil nought....)compression on cylinders 1 and 2 but plenty of air gushing out of number 2 spark plug with the compression tester fitted to number 1 cylinder and vice versa.

i.e. I have a big leak between number 1 and 2 cylinder. Surprised that this gave such a loud "knock"

Anyway it's time to rip the head off.

Good news is that it gives me an excuse to port the head to match the Special Tuning HS8's (original) I dropped on recently, fit the fast road cam supplied kindly by a member on here and re-ring the pistons as the engine has only done 63k miles.

2 months a reckon