Ovaled bores

[davidn]

What are the likely causes of ovaled bores?
The engine's a RV8 5.0l, which was diagnosed with the problem. The engine has done 28,000 miles (under 6000 by me using Mobil 15w/50w).
Any suggestions appreciated.
Thanks
David

[350matt]

Possibly k'ned thrust washers causing the crank to move fore /aft when the clutch is pressed, this would mean the block,rods and crank are also worn. You could tell this by watching the crank pulley and getting someone else to push the clutch pedal it should only move 10-20 thou
Sounds like this engine will need at least a re-bore and new pistons / rings to bring it back to life.
Owch

Matt

[GreenV8S]

It might be the result of labouring the engine too much, but no doubt your engine specialist will advise. Does seem very low mileage for major wear though?

[davidn]

The cause of the ovaled bores turned out to be an incorrectly fitted drive belt causing the water pump to run backwards! Austec spotted it the minute the bonnet was opened.
This created hot spots around the engine especially the water ways around the liners which ultimatley lead to ovaling of some of them. Problem was apart from a very gradual power loss over 6000 miles there was no indication the cooling system was at fault. Temp gauge normal, oil pressure normal, no steam, no change in coolant use.
Still sorted now and lesson learned. It may only be a RV8, and a simple engine (comparatively) but it is still beyond the capability of some fitters.
David


>> Edited by davidn on Sunday 23 May 08:54