300SDL DIY Head Gasket?
 

First of all. Am I crazy to even ask???

If no. Then, how many hours can I expect this to take? What books / tools do I need? How much do the parts themselves cost? Here's the problem, I haven't done much on ANY cars aside from the occasional oil change / filter change / tranny fluid change. Am I crazy for even considering this as a viable alternative?

My mechanic wants $1400.00 for the job. [Which seems pretty good to me] -- I'd like to do it to learn, though.

Thanks,
James

Whitemeadow:

You will need an appropriate wrench set (the head bolts are sometimes hex head, sometimes not), a torque wrench (preferably a "clicker" type), a strong back and a helper. You will not be able to lift the 5 cylinder head off by yourself unless you are pretty husky.

I'm not sure I'd tackle a head gasket replacement as my first "wrench" project unless you have an eperienced buddy to help you -- it's fairly easy to damage the head if you don't understand the instructions!

Basically you remove the valve cover and anything attached to it, the intake and exhaust manifolds, any interconnections between the head and block like water tubes, thermostat housing, etc; injector pipes (you can leave in injectors in the head for just a gasket change). You also need to set the engine at exactly TDC on #1, so that you can CAREFULLY remove the cam gear and tie it up to hole the chain in place.

You then take out the head bolts and pull off the head, manuvering it around the chain -- the chain has to stay pulled up tight so it won't jump a tooth on the injection timer or crank.

Once the head is off, you clean it and the block, put a new gasket on, put it back on, torque the headbolts properly, re-install everything you took off, and you're done.

For a first time job, plan on a weekend. More if you do something like drop the chain, as you will probably have to re-time the injection pump, pull the chain rails, etc if you do......!

Gasket set for a 603 is about $165. Cheap compared to the time to get the head off and back on.

And do check the head while you have it off -- if the head gasket is blown on a 603 (the 6 cylinder), the head is usually cracked and will need to be replaced ------!

Peter

Firstly, thanks for the quick and fairly detailed response. I was under the impression that all 300SDL's are the 6cyl?

I know I haven't ever overheated it [had it since 140,000]-- It's leaking coolant, is why it was taken in, in the first place. I feared some sort of head problem. It just started [noticably] "misplacing" coolant about 1-2k ago. The coolant light would come on going up a hill, then quickly go out as the car leveled off. I added some coolant, then, about a thousand miles later the light started coming on again. So here I am. Is it possible that the previous owner overheated it and the crack has just now become very apparent? Lastly, the question I'm not sure I want answered. How much does a new head cost?

Thanks Again,
James

Don't even think about the price of a NEW head, you don't want to know. There are good machine shops that can repair you head even if it takes welding.

These are aluminum heads so you don't need to be hefty to handle it.

If you are not an experienced knuckle buster, I agree that this would not be a good first DIY project. $1,500 is not a bad price, but see that the head surface is trued and valveguides replaced. In other words the $1,500 should not just be a headgasket replacement, but it should include a complete valve job. Don't even think about spending the money to have the head removed and replaced without doing the valve job while it's off.

Best of luck,

I just had the top end done in my 87 300SDL. Like you, my car started mysteriously loosing coolant. Had no visible leaks, didn't smoke, etc.

These prices are based on memory only, but I've posted extensively about this. Just do a search on my name.

I took the car to the MB dealer in the town my office is located in. At first, I was told it needed just the gasket and estimated the job at around $1800. After it was taken apart, the head was found to be cracked in a few places. The MB part was well over $2000 for a rebuilt head.

I ordered a NEW head complete with valves, guides, springs, etc for around $2200 delivered from MetricMotors (Www.metricmotors.com).

I went ahead and had them do the head, gaskets, and all new valves. By the time I picked it up, the total was around $5200.

Good luck!!

James:

Up to 86 the 300SDL has a five cylinder engine (617). 86-87 have the six cylinder (603)

And replace your radiator cap before you take the head off! They go bad on these cars and either won't hold pressure, hence boil under heavy load (going up steep, long hills, etc) or blow under heat and won't vent, leading to collapsed heater hoses. I've seen two bad ones in the last couple months out of three 87/88 cars -- my 300E (wouldn't hold pressure) and a friends -- collapsed radiator hoses.

Mine only caused trouble if the AC was on and I stopped after a "hot" run on the highway. It would spew coolant until it cooled off.

If there is much pressure in the coolant tank (it hisses or burps hard when you open it cold) you have a bad head gasket.

Hans has been replacing a lot of them recently.

Much cheaper than a head gasket! And in the current state of affairs, some MB dealers will do a head job for coolant loss when the only real problem is a bad pressure cap, sad to say. Make lots more money that way...

If you need a new pressure cap, get a "real" MB one, not one at auto zone or PepBoys, etc. Some aftermarkets are OK, but I'd rather spend the extra five or so dollars, myself.

I definitely have a bad head gasket/head on my "new" 87 300DT sedan -- excess pressure in the coolant reservior and oil, too......! Probably severely overheated as it has a brand new rad in it.....!

Peter

I didn't realize there were SDL's made before 86. At least legally made / imported for / to the US.

I will check the radiator cap, though I'm sure my mechanic already has. I would readily reccomend him to anyone on this list or otherwise. Works only on Mercedes, and has even in the past replaced a part that failed prematurely [no warranty]. They only work on Mercedes, and have always been fair / honest. $50 - hr.

$5200.00. That's nearing the point where you have to start considering what the car is really worth to you... I will search using your name [Lance] and see what I come up with.

Thanks!