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MG MGB GT V8 Factory Originals Technical - Engine sounds dry on startup
|My 3.5 V8 has now done about 2,000 miles and runs fine with about 30 to 35 psi oil pressure when hot. I understand this is acceptable oil pressure but I think I need to give this history to illustrate my problem. The oil pressure was originally 20 to 25 hot with a new oil pressure valve and SDI spring at that stage. I put a spacer in to lift it to the current pressure. The engine has new rings, bearings - main -cam and big end. New Rover lifters too. My concern is it sounds so dry from startup especially if it has not been started for a few days or a week. The oil pressure comes up after a few seconds but the engine sounds so dry during this time and for a few seconds afterwards. To complicate matters it accasionally starts up 'quietly'. I make every effort to keep revs down to a minimum for these first few seconds to minimise this but would like to know if anyone can help. I have a reasonable amount of engine experience and do all my own work but I have limited experience with hydraulic lifters. By the way I made sure the lifter preload was almost spot on .040" if that helps. I have recently changed the remote oil filter adaptor to an English Flotec whereas I had an older centre bolt canister type before, but I don't think this has helped. There does not seem to be very much oil getting to the rocker shafts but the engine is quiet when warm.|
|Exact same thing with my 4.2. OP's 49psi when hot. It rattles and rasps for a few seconds, then all's well. Christ, it sounds like it's about to chuck a rod or something. Most unappealing. It has done this for a long time, though, and runs just great once it gets heated up. I think the only way you could totally eliminate this would be to install a pre-oiler, which seems like a major PITA. I'll just get 'er rebuilt at 100K or whatever.|
|I have exactly the same phenomenon occurring with my 3.5. I often try to blip the starter a bit - switching off before the engine fires and this tends to start the pressure rising. I really don't like it at all but I understand that it is quite normal.|
I'd say that your oil pressure is a bit low. Mine seems to be at 50lbs cold - 45lbs hot
|Thanks Marc and Ted.|
I just thought I would be cheeky enough to bring this up again to see if anyone else can add to this with some technical advice or am I concerned about nothing?
I don't have any experience with this but was thinking about it(I won't say "in my humble opinion" cos' there's no such thing). Anyway, my totaly unqualified and ignorant opinion is: that the MG V-8 is the only car I've seen with the oil filter so high up relative to the engine sump. That in conjunction with the fact that I havn't heard any compliants from Rover owners (perhaps they're bashful) makes it likely that it is this positioning of the oil filter that is the problem. When the engine isn't running it's possible that the oil is draining out of the lines to and from the filter and taking a short while to re-fill (on startup). If the oil filter and lines were relocated down to sump level (perhaps on the rail below the headlight inside the guard) the problem might dissapear. It would make changing the oil filter nice and easy as well. I'm just about to start a conversion and I'll give it a try, thanks for the heads up on the problem.
|A friend has an ignition cutout that as well as an immobilser he leaves off during initial cranking until the gauge registers. Funnily enough, on the two occasions I have checked my compressions, cranking, even with all plugs out (i.e. faster) seems to *empty* the lifters. When I do eventually start up it sounds like the clappers of hell for several seconds even though it has plenty of oil pressure. My lifters and cam do need doing though.|
|Thanks Peter and Paul.|
I think your advice is correct. Peter I have been asking lots of questions locally and I now believe the pipes empty which would never have bothered Rover owners. The V8 Chrysler Valiants sold here in the 1970s had a high mounted remote oil filter because the filter fouled the RHD steering box which was never a problem in the US. They really rattled on cold startup from new and this was just accepted. I spoke with a mechanic who worked in a dealership at the time.
I do wonder if there is a one way valve which would not restrict oil flow which would help?
Paul, I like your idea and will use my starter for a little longer. I have a gear reduction starter which should hurry the process. Thanks.
|Oil filter tucked in behind the front valance might be better than the guard, no stones. Lots of alturnatives really, so long as it and its lines stay low. Got to wonder why MG orrigionaly put it up so high though, perhaps it was a saboteur from the triumph Dpt.|
|I have posted details of an oil reservoir in a similar thread - available I think from Real Steel and possibly RPI.|
|Nigel J S Steward|
|I have found my earlier posting on this topic in February 2001. My memory was correct and Real Steel offer such a pump (I really must get round to acquiring and fitting one).|
Tomo Industrial Estate
Packet Boat Lane
Middlesex UB8 2JP
Phone +44 (0) 1895 440505
Fax + (0) 1895 422047
they don't appear to have a web site, but offer a number of useful V8 bits, including the hydraulic reservoir which is charged with oil when the engine is running.
The oil in the reservoir is automatically released under pressure when the oil pressure falls below a predetermined level when the engine is running, or on start up.
You can choose, one of three methods of actuation. Manual, Electric by a push button or switch, or automatically the first time the starter motor is engergised.
I believe they also offer both electric sump pre-heaters, and electric oil pumps, and electric water pumps, but it is some time since I investigated this problem/solution, so it might be another supplier.
B GT V8
MGA 1600 Mk I Roadster
|Real Steel offer water pumps from Craig Davis. They don't offer any others as far as I know.|
This thread was discussed between 11/05/2002 and 21/05/2002
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