Oldsmobile LF9 diesel engine?
#1
Senior Member
Thread Starter
iTrader: (1)
Join Date: Jul 2006
Posts: 506
Likes: 0
Received 1 Like
on
1 Post
Car: 1989 GTA
Engine: 350TPI w/ Speed Density
Transmission: 700r4
Axle/Gears: Borg warner 3.27
Oldsmobile LF9 diesel engine?
Hey guys, I was wondering. If someone were to be playing with an oldsmobile diesel 350 (the LF9 from the late 70's early 80's) how would I hook up a tachometer to this? I can't imagine a simple way without putting a CPS in or something like, being that it doesn't use an electronic ignition system. It's non-computer controlled so a tach output was never included in one. Does anyone have any ideas?
#2
Moderator
Join Date: Jul 1999
Location: 51°N 114°W, 3500'
Posts: 17,120
Likes: 0
Received 123 Likes
on
104 Posts
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: Oldsmobile LF9 diesel engine?
I don't even know if a tach option was available on the Olds diesel.
Typically, a diesel can get a tach signal from a bunch of different locations depending on the engine. Normally there's some sort of engine position or tach sensor mounted on the engine. It could be looking for a signal from the crankshaft/flywheel, camshaft or injection pump. I've seen some diesels getting a tach signal from the alternator.
Typically, a diesel can get a tach signal from a bunch of different locations depending on the engine. Normally there's some sort of engine position or tach sensor mounted on the engine. It could be looking for a signal from the crankshaft/flywheel, camshaft or injection pump. I've seen some diesels getting a tach signal from the alternator.
#3
Senior Member
Thread Starter
iTrader: (1)
Join Date: Jul 2006
Posts: 506
Likes: 0
Received 1 Like
on
1 Post
Car: 1989 GTA
Engine: 350TPI w/ Speed Density
Transmission: 700r4
Axle/Gears: Borg warner 3.27
Re: Oldsmobile LF9 diesel engine?
Yeah I don't think there was an option for a tach, that's why I was curious. I'll see if I can find one to go off the alternator. I can't imagine there are any sensors on that thing, but it does have electronically controlled EGR vacuum solenoids, etc.
#4
Moderator
Join Date: Jul 1999
Location: 51°N 114°W, 3500'
Posts: 17,120
Likes: 0
Received 123 Likes
on
104 Posts
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: Oldsmobile LF9 diesel engine?
You'll need an alternator with a tach output. Depending on the size of the crank and alternator pulley, the tach signal may not be accurate.
I have no manuals on the Olds 5.7 diesel to see if there's a tach sensor. It's not a popular engine.
I have no manuals on the Olds 5.7 diesel to see if there's a tach sensor. It's not a popular engine.
#5
Senior Member
Thread Starter
iTrader: (1)
Join Date: Jul 2006
Posts: 506
Likes: 0
Received 1 Like
on
1 Post
Car: 1989 GTA
Engine: 350TPI w/ Speed Density
Transmission: 700r4
Axle/Gears: Borg warner 3.27
Re: Oldsmobile LF9 diesel engine?
Yeah they came from the factory with weak head bolts causing many cylinder head blowouts. The motor is from a 1982 cadillac deville and is probably staying there to be restored. The head bolts were replaced with the aftermarket kit to fix this issue. Ill have to search the internet more in-depth to see what other people have done, I just wanted to see if anyone here had any experience with the engine
#6
Moderator
iTrader: (14)
Join Date: Mar 2000
Location: Littleton, CO USA
Posts: 43,169
Likes: 0
Received 35 Likes
on
34 Posts
Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
The original engine? Pretty rare for them to last until the '83 model year when they started sorting out the problems (like aforementioned head bolts which were torque-to-yield; and 10W-40 oil which crudded up the roller lifters and caused cam failure, solved by going to 10W-30 oil).
#7
Senior Member
Thread Starter
iTrader: (1)
Join Date: Jul 2006
Posts: 506
Likes: 0
Received 1 Like
on
1 Post
Car: 1989 GTA
Engine: 350TPI w/ Speed Density
Transmission: 700r4
Axle/Gears: Borg warner 3.27
Re: Oldsmobile LF9 diesel engine?
Yep, it's the original engine. It either has 83,000 miles, or 183,000 miles (the tach only has 5 whole number digits). Hey, since I'm on here, can anyone locate the camshaft profile for this engine because I was wondering if I could swap it out for a closely related gasoline 350 cousin, for better power.
Trending Topics
#8
Moderator
Join Date: Jul 1999
Location: 51°N 114°W, 3500'
Posts: 17,120
Likes: 0
Received 123 Likes
on
104 Posts
Car: 87 IROC L98
Engine: 588 Alcohol BBC
Transmission: Powerglide
Axle/Gears: Ford 9"/31 spline spool/4.86
Re: Oldsmobile LF9 diesel engine?
I wouldn't go swapping a gasoline camshaft into a diesel. Valve timing is completely different. Because of the high compression, chances are the valves are close to making contact with the piston already.
#9
Junior Member
Join Date: Apr 2008
Location: Griffin, GA
Posts: 65
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1987 Camaro
Engine: Oldsmobile 455
Transmission: Th-700r-4
Axle/Gears: 3.23
Re: Oldsmobile LF9 diesel engine?
Yep, it's the original engine. It either has 83,000 miles, or 183,000 miles (the tach only has 5 whole number digits). Hey, since I'm on here, can anyone locate the camshaft profile for this engine because I was wondering if I could swap it out for a closely related gasoline 350 cousin, for better power.
www.Oldspower.com
www.realoldspower.com
I have a 1981 Cutlass with a 350 Olds. In fact it alrdy sold and I havn't even removed the engine yet. I have a nice 455 ready to install. I figure I would never have the time and money to make my 350 diesel to it full potential so y not make some money and let someone whos does have it.
But far has a tach. Your alternator should have a tach wire slot. But if yours is like mine you don't becuz someone most likely installed a reg alternator off a gas burner.
Thread
Thread Starter
Forum
Replies
Last Post
84z96L31vortec
Tech / General Engine
7
08-20-2017 12:16 AM