A fookin bearing toasted the engine!
#1
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Got a call from a friend with a 99 XK8 with his AC not working & engine overheating. Picked up a belt from pep boys & went to meet him. His engine was too hot to touch even after a good 45 minutes after it came to a halt!
Looks like the idler pulley (next to the alternator) bearing had failed & thrown the belt (Took me an hour to dig the belt out the engine). The bolt depicted in the picture & the 2 rings (outer & inner bearing housings) are what left of the pulley & its bolt!
This lead to extreme overheating that ruptured the expansion tank & loss of most of the coolant!
Towing the car to the shop i started with a compression test thinking head gaskets at worst but am greeted with a big fat ZERO, 0, nada, nil, nothing compression in ALL cylinders. Used 2 gauges to make sure & tested each cylinder multiple times! Just to make sure, took out all plugs & still "nothing" when cranking the engine!
Tough break for my friend all over a bearing!!
Looks like the idler pulley (next to the alternator) bearing had failed & thrown the belt (Took me an hour to dig the belt out the engine). The bolt depicted in the picture & the 2 rings (outer & inner bearing housings) are what left of the pulley & its bolt!
This lead to extreme overheating that ruptured the expansion tank & loss of most of the coolant!
Towing the car to the shop i started with a compression test thinking head gaskets at worst but am greeted with a big fat ZERO, 0, nada, nil, nothing compression in ALL cylinders. Used 2 gauges to make sure & tested each cylinder multiple times! Just to make sure, took out all plugs & still "nothing" when cranking the engine!
Tough break for my friend all over a bearing!!
#2
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Well how long did he cruise along with the belt gone if he only ever noticed "his AC not working & engine overheating"? No squealing? Steam pouring out?
That may be a nikasil block. If so, the overheat may have burned off the oil on the cylinder walls and so it is not sealing. Try again after squirting some oil in each bore. You wouldn't lose compression on every cylinder of an 8 cylinder motor at the same time.
That may be a nikasil block. If so, the overheat may have burned off the oil on the cylinder walls and so it is not sealing. Try again after squirting some oil in each bore. You wouldn't lose compression on every cylinder of an 8 cylinder motor at the same time.
Last edited by plums; 06-25-2011 at 10:19 PM.
#3
#4
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He was going a steady 75 for a good 10 minutes after he lost the belt. No reports of steam but evidence of plenty of coolant covering the engine bay & drivers side front fender.
compression in all 8! im certain. will check again after oil trick.
No compression is also perplexing to me as ive never seen it first hand but im certain of it. I checked & checked again in all cylinders with 2 compression testers as i also was finding it hard to believe. I wont giver up yet.![Smile](https://www.jaguarforums.com/forum/images/smilies/smile.gif)
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Well how long did he cruise along with the belt gone if he only ever noticed "his AC not working & engine overheating"? No squealing? Steam pouring out?
That may be a nikasil block. If so, the overheat may have burned off the oil on the cylinder walls and so it is not sealing. Try again after squirting some oil in each bore. You wouldn't lose compression on every cylinder of an 8 cylinder motor at the same time.
That may be a nikasil block. If so, the overheat may have burned off the oil on the cylinder walls and so it is not sealing. Try again after squirting some oil in each bore. You wouldn't lose compression on every cylinder of an 8 cylinder motor at the same time.
No compression is also perplexing to me as ive never seen it first hand but im certain of it. I checked & checked again in all cylinders with 2 compression testers as i also was finding it hard to believe. I wont giver up yet.
![Smile](https://www.jaguarforums.com/forum/images/smilies/smile.gif)
#5
#6
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I will pull the heads & post up.
The valve seats often drop and bend valves when abused/overheated like that. 10 minutes with no water circulation? Tough to say over the internet....but if I were a bettin' man, I'd say the engine is done. Your buddy should have pulled over as soon as he noticed the issue.
#7
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Performing a leakdown & valve clearances tests gave negative results so i pulled the heads. They are at the machine shop where im getting a quote for new valve seats only on the ones that came off, new valves to replace the bent ones' resurfacing etc.. etc...Some of the pistons have been stamped pretty good by the valves but it looks cosmetic & cylinder walls look fine...
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