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MG MGB GT V8 Factory Originals Technical - Motor startup: no OP?
|I just spent a fortune having my Rover V8 rebuilt and slightly modded. I'm wondering whether there are any per-oiling things you can use to cut down on wear from still startups. The shop noticed a ton of wear on the motor despite modest mileage, and suggested to me that the motor must be running without oil for a good bit until the pressure comes up. Any easy solutions? |
(I'm not sure exactly why this is, in that soccer moms typically start up their Range Rovers and go, and to my knowledge there's no huge problem. But these guys are thought to know what they're talking about, and if they tell me the engine's starting dry, so it must be.)
Have always used Mobil 1, except for run-in, if that matters.
|I haven't been on this BBS for ages, as I no longer have an MG, but FWIW: I have a late-model Triumph 3-cyl. motorcycle which does something I wonder why more motor vehicles don't do. When you press the starter button, it doesn't light the spark plugs for a few seconds but merely spins the motor, I guess to splash around some oil, etc. Also to cut down on startup stress, if you open the throttle even a hair, the sparks are disabled. Advises you of this in the owner's manual so the owner won't think it's sluggish starting. Wonder why they don't do this on more cars ... surely it preserves the motor a bit. |
Of course since the bike motor runs at 13:1 compression maybe this would be that much more of an issue; I dunno.
|I don't know how you have your oil filter arranged(remote?), but could the filter be draining back to the sump when the engine isn't running and require re-filling before you get pressure? A good anti-drainback valve on the filter would prevent this.|
|check the pressure relief spring and valve,I had problems with an engine that had sat for 18 months, It had the higher tensioned BV8 spring in it , dont know what caused it ,but on startup the oil light went out,[pump was picking up,engine was in TR8,no gauge]valve was jambed ,returned most of the oil to the sump. Put in old standard spring ,pressure back to normal.|
Number one thing is have an oil pressure test done on the engine and find out what shape the pump is in although if the engine has just been rebuilt this should be supplied by the rebuilder.
If it has not been done the builder is incompetent and I would be lookibg somewhere else.
Sarting from cold and driving straight off is exactly what most car makers recommend in the handbook so it should be no problem. As a related point my 3.8 V6 has 481,000 kms (about 240,000 miles) and I have always done precisely that. No rebuilds and the oil pressure is as per the book. The oil by the way is 20W50.
What was done on the engine prior to the rebuild should have no bearing on what happens to the engine afterwards since the rebuild should mean a brand new engine.
Car makers have emissions levels to contend with so spinning the engine without firing the mixture is not an option for them.
It does as you rightly state reduce wear.
You have the advoce you need but if you want a long life engine have a look at a pre-oiler
You have the luxury of space
|My oil pressure is always very slow rising from cold, but it does *start* to rise immediately. Equally slow to lose pressure when switched off cold. Whilst I don't leave mine idling to 'warm up' I do wait for the pressure to rise to its max cold value before driving off. There are so many of this type of engine with very high mileages that any general problem would be well known, if yours really was worn I would suspect something specific to your engine. |
The MGOC in the UK has recently started selling Unipart GFE 121 F oil filters - the F is said to signify manufacture by Fram with an anti drain-back valve as opposed to the GFE 121 without the F. I have never had drain back problems with these (non F) or Champion filters on either my V8 or my roadster but someone else earlier this year said newly purchased units of both when used inverted gave instant drain back such that the filter was empty on changing and was giving a delayed (rather than slow) gauge rise. But having said all that the factory V8 has a hanging filter which can't drain anyway.
|Peter I don't follow; how does cranking the motor a bit w/o igniting the spark plugs increase the motor's emissions? Does it make an oil mist or something that gets dirtily burned when the motor finally fires? |
(Don't get me wrong ... you must be right ... when I first bought the bike I was like, why on earth doesn't every car do this it basically solves the bulk of the wear problem ... when I had a BV8 the pucker factor was pretty high when the motor would start, no OP for a few seconds and it sounded like a bunch of huge ball bearings rattling around inside the motor for a few seconds then all was well. Possibly putting on one of Dan L's low-mount oil filter brackets -- rather than having it up on the fender as I did -- would help a bit if you could fit it what with the sway bar and so forth.)
My MGB engine used to rattle like hell on start up, in fact the shop manual indicates that it is a good idea to replace rod bearings every 40,000 miles, I guess to compensate for this malady. Now I am installing a 3.1 Fuel injected v6 with 5 speed and all of the computer and emmission stuff (you do like breathing good air don't you?)The engine will not run until the oil pressure is up to a preset level - good feature. Anyone can install the switch that is used. It has a set of contacts that become connected when the oil pressure pushes up with enough pressure to overcome the spring inside. If you loose pressure while running, the engine stops before if detonates into small pieces. Connected to the electric fuel pump.
No pressure - No electricity - no gas - no run FWIW Alan
The oil pressure switch on the electric fuel pump is more effective with fuel injection than it is with carbs. With carbs you will hope that the bowls run dry before too much damage is done. The pressure switch also helps shut off the fuel in a rollover for cars not equipt with inertia switches for that purpose. Sometimes the pressure switch is bypassed during cranking to prevent excessive cranking and starter wear.
|There are several car models that spin the engine a few revolutions before starting the engine. The injectors are not pulsed rather than not igniting plugs. No emmissions to worry about. Many car manufacturers, especially before heated oxygen sensors were introduced, recommended that you drive off immediately in order to get the engine into "closed loop" as quickly as possible. "Open loop" is the time that the computer feeds fuel based on a predetermined fuel map and once the oxygen sensors are good and hot the computer goes closed loop and uses the oxygen sensors to fine tune mixture.|
|David - cranking a carb engine without spark pumps unburnt fuel through the exhaust. Depends on whether unburnt fuel is considered to cause worse emissions than burnt fuel or not.|
|Got it Paul. Bike's fuel injected so hopefully they have it rigged so there's no gas being expelled until it's time to fire the doggone thing up. I do see your point for carbureted motors though.|
This thread was discussed between 21/10/2003 and 23/10/2003
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