through a friend at work i have come across an opportunity to purchase a 79 300SD. i think a W116. what are your guys thoughts on this?

it has somewhere between 200K & 240K miles, dont remember. unknown maintenance history. it was supposedly passed down from a guy to his son and then to his son in-law. it was driven for a short while, said it ran great, and parked for a few months. when he tried to start it again it would turn over but not start. lost its prime???

as he (son in-law) does not know anything about diesels he is now looking for a buyer.

the interior is said to be in excellent condition. the only known problems other then the no start issue is some of the clear coat is peeling on the top of the car and the trim strip on the driver door is missing.

i am going to see if i can take a look at it this weekend and maybe get it started. i may not want to get it running with the seller around as he may back out or raise the price. what would be the max you would pay for this vehicle?

i dont know a whole lot about these tanks but i have read that i will need to adjust the valves and clean/adjust the ALDA

it is supposed to be rated at 110HP. can this engine practically make more HP?

thanks for any helpful responses

 

A model from '79?
Heck, that thing is 32 years old. Get a syringe and inject a bit oil into the chambers- if the thing starts- compression is lost because of worn piston rings. If not, valve seat re-adjustment necessary.

Sure there is more hp, just google the you tube pages- there are plenty of turned up IP mercs.

 

"Get a syringe and inject a bit oil into the chambers"
do i pull the glow plugs to do this?

would worn rings cause this engine to suddenly not start or is it something that will cause it to get worse over time?

sorry for some of these questions. i know very little about these engines and not having seen it yet makes it worse

 

no, you open the service airlocks...

Of course you do have to remove the glow plugs!
Worn rings does not necessarily mean bad compression. But a combination of worn rings, worn liners, neglected glow plugs and/or valve seats can lead very easily to this phenomen.

The extra oil you inject will seal the gap for a short time. If not, the owner is telling you bull.
Make also sure there is enough fuel in the pump. Mercs do have a hand activated pump- use it.

 

well i have tried several things to get it started to no avail.

tried a good 50A jump starter to see if the battery was just week, nope

tested glow plugs, one not working. all others pulling about 22 amps each

primed and cracked the injector line loose, cranked till fuel came out. tightened them back up, still wont fire.

adjusted intake and exhaust valves. found two intake and one exhaust that where too tight to slip the gauge in. still a no go

tried starting fluid. not even a sputter

pulled the plugs and squirted oil into the cylinders. it tried to start this time but only a few hiccups and then nothing

this was all done with the help of the engine starter while turning it over. seems to me that he my have some serous ring/cylinder issues, as the only time that the engine even had a slight hint of starting was after squirting oil into the cylinders.

what do you guys think? abandon all hope? is a ring/hone job difficult or expensive for these engines?

he is now asking $600 after seeing everything done and it still didn't start.

is there anything else to test or try? what about fuel pressure? pull an injector and see if it sprays during cranking? don't know if these engines will have any white (unburnt fuel) coming out of the exhaust if the compression if bad but i saw nothing.

here are a few photos for you guys

 

It is just a normal IDI engine.
Get a compression tester and check it to know exactly. Air filter / fuel filter clogged? Exhaust bend?
Try external fuel supply from a jerry can.
Try to talk him down and pull that thing home- it looks nice.

 

Do you know what the normal psi for compression on these engines is supposed to be?

I did try loosening the banjo bolt for the fuel line going to the injection pump and got plenty of fuel while priming. With the injection lines loose fuel was coming out of the lines when cranking. Whether it is high enough to open the injectors is still unknown.

We did remove the cover on the air filter while trying to get it to start so I dont think it would be the air filter

If it Is bad compression, is it just pulling the pistons out, replacing the rings and honing the cylinders? From what i have been reading, it sounds like it is not normal for these engines to go through this kind if work at only 240k miles. Makes me wander if it was run low on oil or coolant and overheated or something. What else could be wrong with it if it was.

It does look pretty nice with only a little bit of the clear coat peeling. I may be able to get it for $500. I don't know yet how involved it be get to get this thing running. I did some internet searching and there seams to be several others around me that are selling 83 and 84 300sd's for between 2 and 3 grand running, and seem to be in just as good shape if not better. Some have comparable miles while others are unknown. Do you think I should pursue this one for $500 or look elsewhere for $3k?

Thanks for your help so far. I am still learning a lot about this particular engine so there may be more questions to come

Jason

 

I would check the fuel shut off too.thats why I have written to supply fuel via a jerry can. You can remove the shut off plunger- so the engine will run.
I don't know the exact compression ratio nor the pressure but I know that each chamber must be within 3 bars or within 50psi of each other.
At least it seems to be a good source of spares.

 

thanks.

if i get another chance to look at it i will give it a try

 

140hp with some work. However, your transmission is a weak design and cannot handle more power like the 81+ models.

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300-450psi.