Driving home tonight, the oil warning light started to light when the engine was idling at junctions, but went out when the revs increased. I checked the engine oil level and it was up to the full mark , after letting it stand for a few minutes. There is also a knocking noise. The engine is a 3.9 v8 EFI, if it's the original engine, the speedo reads 168,000. Could it be the oil pump broken or is it likely to be something like the big end gone? Thanks.
Bill Payer uttered summat worrerz funny about:
If it's gone all of a sudden then I'd look at the pump first. Regardless it's done you proud at that mileage.
Lee D
At that mileage it's done very well! You can try a new pressure switch, they have been known to lie, but in all honesty it's more than likely time for an engine rebuild at such mileage. probably need a crank grind for mains and big-ends, rings, cam bearings, cam & followers etc etc. Then it'll be good for another 168,000....... Badger.
Just as a matter of interest what would you exepect to pay for that sort of major re-build? Is it better to get a recon engine? At 145000 miles my v8 still seems to be going strong despite my lack of attention over the years and a pretty hard life towing. A re-build would be beyond my abilities so it would be nice to have some figure in mind in case it become necessary.
Les
Varies widely, but having the cam, lifters and chain done on my Disco
3.9 cost under £300 including the parts. I thought that very cheap (which is what I always think when Warren gives me a bill). He did it with the engine in, which made life easier. Had to drain the aircon though 'cos the air-con radiator had to come out.Obviously doing the bottom end is going to be a bigger proposition. I would have thought it reasonable to expect a fairly firm quote.
If the engine is coming out, is it wise to replace the clutch as well?
you might have spun a rod bearing , common thing on v8s, usually number
7 cyl it will be .knocking noise depends on type of noise and where from, if its a ticking noise that will be the came area probably, if its a thudding or ding ding noise then probably the crank .
to make a start you could drop the sump off and check rod bearings on number 7/8 cyls , just take cap off number 7 and 8 rods and see if there is a step in the middle of the crank journal somewhere and also if one of the rod bearings has rotated in the rod end and cap .
if youve spun that bearing then youll need a new conrod and the crank grinding on that journal in the least .
you can do the crank in the engine but really the heads will need to come off and to be honest it wont be an easy job to put crank in and torque all the bolts up and set everything up . better option would be to find another engine and swap over , or to build another engine up for it or buy a reground crank from someone like REAL STEEL or v8tuner.co.uk .
problem with getting reground crank is that if any of the rods have gone youll still need to replace these as well .
usually with any bearing trouble at the crank it will be noticeably noisey upon a cold startup in mornings after being left overnight .
if you drive with knocking rod bearing then you could end up putting a rod through side of the block and completely wrecking it all , so if you want to save the engine for a rebuild its best to forget drving the vehicle and set to work on it right away .
Bill Payer wrote:
Not when I did it it didn't. There was enough slack in the air-con hoses to move the rad enough to slide the cam in and out.
John
I started it up tonight after leaving it over night, it fired up with little to no noises. Is this any help in diagnosis??
Could be a hydraulic tappet, but that wouldn't explain low oil pressure..... Badger.
Hi
In my experience, I have had this problem with a sticking piston on the oil relief valve on 3.5s.
It's not a big deal to fix, but the pump has to be primed with Vaseline and you get strange looks in Boots when you say "haven't you got a larger jar than that"
Regards
Can't you use ordinary grease ? I've always wondered.
Steve
No, it can carbonise in the crank oilways and block them. Badger.
That's probably saved an engine....
Steve
On or around Mon, 26 Dec 2005 23:18:34 +0000, Steve enlightened us thusly:
summat about the vaseline dissovling in the oil, and ordinary grease doesn't, properly. It's reputed that only vaseline works, anyway...
I've had the same symptons as decribed in the OP in a saab which were due to the oil pressure relief valve. My oil light always used to come on when i came off the dual carriageway/motorway and stopped at the slip road. And occasionally at junctions. Put your foot down a little and it would usually go out.
I dont know v8 engines intimately (yet!) so i didnt know if they were the same - but it sounds like they are.
If I pulled the relief valve, how can I tell if it's OK? Also, it might be nothing , but in the last couple of weeks when I first started up, it would take about 5 - 10 seconds for the oil warning light to extinguish after the engine had been started from cold. Could this also be something to do with the oil pressure relief valve? Thanks..
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