79 450SL won't rev up
#1
12-05-2004, 09:41 AM
79 450SL won't rev up
I have a 79 450 SL that I am trying to resurrect from the dead. It will start and idle but I am having trouble getting it to rev up. I can get under the hood and and advance the throttle & then push down on the air intake plate ( I don't know the proper terminology) and when you get it at the proper setting it will rev up. I thought it was a fuel problem and have replaced the injectors, the fuel pump, the filterand the fuel accumulator. Also I would like to know where I can get so sort of repair manual for this model. Any help or thoughts would be appreciated.
#4
12-06-2004, 12:23 AM
RE: 1976 450SE
how to lock the door?
real men must have two things only to do everything.
1. WD-40
2. Duct tape
if it moves when it is not suppose move, use the duct tape.
if it doesn't move when it is suppose to move, use the WD-40.
real men must have two things only to do everything.
1. WD-40
2. Duct tape
if it moves when it is not suppose move, use the duct tape.
if it doesn't move when it is suppose to move, use the WD-40.
#5
12-06-2004, 05:38 PM
RE: 79 450SL won't rev up
www.manualsunlimited.com has manuals on CD for $23. I got one for my 88 SL560 & it's great.
#7
12-08-2004, 10:37 PM
RE: 79 450SL won't rev up
Bugs,
Your manually controlled jetronic fuel injector system has a lot of vacuum lines that you should check. Most of the originals will be plastic lines with rubber connectors (like Ford--stupid design). These get brittle and fail. Take the air cleaner off and check them all carefully following them to each end to make sure that there are no leaks, cracks or breaks. Replace any that you aren't sure of with a length of all rubber vacuum line.
Is the timing and air mixure set properly? Have you replaced the plugs and wires? I believe the timing on the '79 is O deg TDC. You set it just like a pre-electronic ignition car with a timing light, turning the distributor. You probably will need to mark the TDC line on the balance wheel in white paint, which you can do from underneath the car. Turn the engine a little with a wrench on the end of the crank or using a fan belt to turn it until you can see the mark (a scribed line marked 0deg or something similar) The right angle timing pointer may also need to be highlighted to see. (Look down from the top through the belts, just to the side of the front of the crankshaft to see it). I assume you can use a timing light. The mixture setting is down a small recess directly in front of the air intake inderneath the air cleaner. You need a 3mm hex key about 4-6 inches long or longer to adjust it.
Oh, one other thing. You said you can get the car to accellerate by manually opening the air intake valve. Tehre are two simple things you can do to make sure this is adjusted properly. The first is to clean it along the edge of the valve, both the flat disk and the underside of the seat that it closes on. The other is to see that it is centered properly. You can do this by cutting three strips of copy paper about two inches wide and stick them under the lip of the valve so taht half of the paper is above and half below the disk, equally spaced apart. Try pulling them up one by one. There will be a gentle friction or they will just catch. If any pull out freely, then you need to loosen the nut in the center and move the disk until there is equal resistance along all edges of the valve. Retighten and you have it.
You also might have a bad EGR valve or plugged exhaust gas connection at the valve cover. You can clean out the latter with the right sized twist drill (trial and error I can't remember the size). Don't drop the drill inside! The EGR valve is located on the left side of the engine compartment toward the front. If you can get your finger up underneath, there is a little opening where you can push in the valve gate if it is working smoothly. Replacing the EGR valve isn't cheap. EGR valves only operate at lower rpm so if the car stalls when accellerating at high rpms, it proably isn't the EGR.
As far a manuals go, the best aftermarket one is the Haynes manual. You can get a CD-Rom copy of the original Mercedes 450sl repair manual on Ebay. It's a little wordy but has all of the 450 model years. They are about $20 and always show up.
Your manually controlled jetronic fuel injector system has a lot of vacuum lines that you should check. Most of the originals will be plastic lines with rubber connectors (like Ford--stupid design). These get brittle and fail. Take the air cleaner off and check them all carefully following them to each end to make sure that there are no leaks, cracks or breaks. Replace any that you aren't sure of with a length of all rubber vacuum line.
Is the timing and air mixure set properly? Have you replaced the plugs and wires? I believe the timing on the '79 is O deg TDC. You set it just like a pre-electronic ignition car with a timing light, turning the distributor. You probably will need to mark the TDC line on the balance wheel in white paint, which you can do from underneath the car. Turn the engine a little with a wrench on the end of the crank or using a fan belt to turn it until you can see the mark (a scribed line marked 0deg or something similar) The right angle timing pointer may also need to be highlighted to see. (Look down from the top through the belts, just to the side of the front of the crankshaft to see it). I assume you can use a timing light. The mixture setting is down a small recess directly in front of the air intake inderneath the air cleaner. You need a 3mm hex key about 4-6 inches long or longer to adjust it.
Oh, one other thing. You said you can get the car to accellerate by manually opening the air intake valve. Tehre are two simple things you can do to make sure this is adjusted properly. The first is to clean it along the edge of the valve, both the flat disk and the underside of the seat that it closes on. The other is to see that it is centered properly. You can do this by cutting three strips of copy paper about two inches wide and stick them under the lip of the valve so taht half of the paper is above and half below the disk, equally spaced apart. Try pulling them up one by one. There will be a gentle friction or they will just catch. If any pull out freely, then you need to loosen the nut in the center and move the disk until there is equal resistance along all edges of the valve. Retighten and you have it.
You also might have a bad EGR valve or plugged exhaust gas connection at the valve cover. You can clean out the latter with the right sized twist drill (trial and error I can't remember the size). Don't drop the drill inside! The EGR valve is located on the left side of the engine compartment toward the front. If you can get your finger up underneath, there is a little opening where you can push in the valve gate if it is working smoothly. Replacing the EGR valve isn't cheap. EGR valves only operate at lower rpm so if the car stalls when accellerating at high rpms, it proably isn't the EGR.
As far a manuals go, the best aftermarket one is the Haynes manual. You can get a CD-Rom copy of the original Mercedes 450sl repair manual on Ebay. It's a little wordy but has all of the 450 model years. They are about $20 and always show up.
Thread
Thread Starter
Forum
Replies
Last Post
