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Diesel starting problem....[700/19-- (don't know)] posted by Alex on
Friday, 6 April 2001, at 9:39 a.m.
Hi,
I have a friend with a 740 Turbo Diesel wagon that just cranks and cranks and cranks and won't start. He demonstrated it for me and was cranking for atleast 30 seconds and nothing. THe sound of the engine did change a tiny tiny bit (only discernable to people who know something about cars). Any common problems or is it just bad compression or a shot engine? Thanks for any help you could give us. Is it time to junk this car?
Alex
Crude Minnesota farmer method to test glo-plugs[700/19--] posted by Jim Baron on
Friday, 6 April 2001, at 2:54 p.m.
If and only if you know enough about glow plugs to recognize the wiring on the plugs themselves, take your jumper cables and connect the red handled cable only first to the positive pole of the battery and then to the glow plug wire -- leave it connected for not more than about 10 seconds, and then disconnect and try to start the car. If it starts immediately, you have a problem somewhere in the system of wires and relays and timers between the ignition switch and the main glow plug wire. If it still doesn't start, it may be in the glow plugs themselves (although they rarely fail all at once -- has your friend been having rough running at first start up progressively getting worse for some time) or a matter of worn rings. The problem with turbo-diesels, at least those built by VW (including those with "Volvo" on the cam covers) is that they have lower compression to compensate for the turbocharging at speed on the autobahn, and are therefore fundamentally hard starting, and any loss of compression makes it get intolerably bad fast.
And if your friend decides to sell the car, and it's a station wagon, and anywhere near Williamsburg, Virginia, get back in touch with me at jamesrbaron@cs.com
Addendum[700/19--] posted by Jim Baron on
Friday, 6 April 2001, at 3:07 p.m.
You are dealing with a motor with timing belts -- a main one for the crankshaft to camshaft connection, and, I believe (memory worries me on this, I must admit) also a small one from the rear of the camshaft to the diesel injection pump. Could it be that the latter is broken? If the former were broken you would know it by now on a diesel because of all the banging sounds as parts which shouldn't touch destroyed one another by contact.
Re: Diesel starting problem....[700/19-- (don't know)] posted by Robert Ludwick on
Friday, 6 April 2001, at 8:05 p.m.
Definately try Jim's glow plug jumping test first ( I've used that one many times myself ) if that doesn't do it change the fuel filter , a diesel filter can clog dead-in -the-water almost instantly after getting a bad batch of fuel.
IF jumping the glow plugs doesnt do it , here's another one ( don't try this at home kiddies): take a propane torch and gently and evenly heat the head(s) up. take your time, make sure to heat evenly ( dont concentrate on any one area) and dont catch anything on fire.
After the head is good and warm to the touch all around , if you have fuel, it will fire( I even got a VW diesel with dead glow plugs, whole circuit shorted ,catastrophic failure started at 10f and snowing with this method... but it took over an hour )
Good luck-------Robert
Robert Ludwick
Re: Diesel starting problem....[700/19--] posted by Herman,Cherry Turbos on
Saturday, 7 April 2001, at 7:29 a.m.
Alex, a Volvo diesel with dead glow plugs should always start, IF and only IF the injectors are properly atomizing the fuel. In time the injectors allow fuel to dribble into the pre-chamber and the onto the glow plugs. The glow plugs then vaporize a little of the fuel and heat it at the same time, providing just good enough conditions to start the motor. However properly atomized fuel will also start the motor (down to approx 28 degF) every time with a little extra cranking. The Bosch injector nozzles are notorious for erosion and then pintle failure. Replacing the nozzles in the injectors can be a DIY job if cleanliness and notetaking are observed.
--The price has been lowered on 240 brace kits!!(good exchange rate)
Re: Diesel starting problem--several possibilities[700/19-- (don't know)] posted by chris herbst on
Saturday, 7 April 2001, at 10:00 a.m.
You can easily establish whether or not it is strictly a glow plug problem or another, more serious issue. You should have already established that the timing belt and the injection pump drive belt are at least intact.
Don't do this without reading carefully.
Get a can of starting fluid, otherwise known as ether or diethyl ether. Disconnect the glow plug wire from the glow plugs, or pull the glow plug fuse. You need to VERIFY that the glow plugs aren't working, so choose your choice of methods, but make SURE they arent.
Note: If they are, you stand the chance of killing the engine once and for all. Ether has a tremendous amount of stored energy and will crack pistons and bend rods if ignited prematurely by the glow plugs.
Open the air intake box so that you can shoot the ether right into the intake hose.
Spray the recommended dose of ether into the intake hose.
Get in the car and turn the key right to "start". This blows off the glow plugs just in case you didn't somehow deactivate them to begin with.
If the engine will run at all, it will do it with the ether. You can ALWAYS start a cold diesel engine with ether, as long as it doesn't have a mechanical problem that prevents it from running in the first place. This even goes for engines with far-below-spec compression figures, which often run fine when warm, but have a hard time starting. Many old GM 6-71 engines run like this.
Another area to investigate is the pump function itself:
Volvo injection pumps are self-priming, but that feature sometimes goes sour after years of use. Symptoms include rough idle, heavy white smoking and low power, and stalling after extended periods of idle. Cranking for up to 30 seconds is common when the pump loses prime in such a way. This problem can literally appear overnight on the rotary type injection pumps like the Volvo's.
If the problem is fuel starvation, sometimes adding an electric assist pump will solve the problem. This is a very cheap but effective solution to a very common problem. The only other way is to replace the injection pump.
One more thing to make sure of is that the gasket on the fuel filter is not cracked and is seated properly. That will cause the same kind of problems as a poor internal priming pump.
--chris herbst, milwaukee, WI ---- four Volvos