Sooo, I now have 5 miles on my newly rebuilt engine (4.2 6cylinder )
when it started making loud scratching noises coming from the front of the engine. I shut it off quickly, poked around a bit and gave it compression test,
everything was fine. I then looked on all the Jag web sites and had a bunch of jag enthusiasts look and study the cause of the noise. First I checked the water pump then the alternator, then the distributor, everything seemed fine ???
In my rebuild I had replaced rings,valves, guides, cam bearings main bearings,rod bearings, distributor, clutch, trans bearings etc. BUT had not touched the timing chains and the tensioners, these seemed to be in excellent shape so I left them alone. This car only had 35,000miles on it, but it had sat dormant for 35 years so some things needed to be replaced mostly because of corrosion ! So everybody says it has to be the timing chain tensioners, they have lost the rubber wear surfaces even though they are not worn out ! So off comes the timing chain cover and upon close inspection they are determined to be in excellent shape ! I was at my wits end, what to do ?? everything was reinspected and found NOT to be causing the noise! So I took a chance and started the engine with all the covers off (valve covers, timing cover, etc)
The engine ran as quiet as a mouse. I then started to reinstall all the parts back on the engine, thinking I haven't fixed the problem but it seemed to go away !
Now when I picked up the water pump which some previous owner had rebuilt with all new stainless shafts and bearings I noticed it would only turn in one direction !! upon closer examination I found rust particles in between the impeller and the housing ! if the pump was turned by hand with the rust particles in the "right" spot it made a NOISE if the pump was turned over it was quiet! " DAMN" its so hard to believe the damage an engine can suffer by sitting dormant so many years !! The pump is cleaned of rust and back in place and the engine is nice and quiet, who would have thought this would be the source of the engine noise, especially after checking the pump for bearing
wear ! I have driven the car hard with that pump and it is still quiet !
I think this is "one for the books".

 

Just for giggles , when you started the motor for the first time.........Did you prime the system with oil?
That sounds like the same effect as well.......
Now drive the thing till the wheels fall off, when your gone, no one else will want it........
Enjoy the ride.
GTJOEY1314

 

dear gtjoey: The jag always has had good oil pressure (60lbs cold) and if you read my post
I had no problems with oil pressure ? So I don't understand your response.

I posted this blog to educate and inform other jag owners about a little known
cause of engine noise that nobody seemed to be aware of !

This is what Jaguar Forums are about, to help, to inform and to educate, not
for ridicule!

 

felinecat, I'm not ridiculing at all.......Your statement ended with a question mark. I'm just stating you had a scaping metal sound. If the engine is rebuilt and the motor is not primed say with a drill , your cranking dry till the oil pressure builds up around the entire block.
Just a step some people miss or if you don't use heavy gear oil for the cams and all.
Believe me we are on the same page..
Enjoy.
GTJOEY1314