How to keep a 14 head OM603 going as long as possible? - PeachParts Mercedes-Benz Forum

robertb1958 · #1 12-22-2018, 11:35 AM

I am a glutton for punishment, I guess. Just got another OM603 car, this time it’s a sedan. Last year, I got an 87 Wagon, found that it had a bad “14” head, and swapped in a lower mile engine with “22” replacement head already on it. The wagon runs well.

I bought the sedan thinking it would be a parts donor car, but the sedan runs great, actually better than the wagon. It seems fast! And has heated ortho leather seats in great shape same color as the wagon (why I bought the car). So I am driving it now.

So, the point of this post is to ask: How to maximize the life of the 14 head?

Obviously, keeping the cooling system in good shape will help. The wagon I have runs just above 80, dead steady even in the summer with AC. The sedan temp floats between 80 and a little below 100, even in cold weather and with heat on the highway. Sort of tempting to change the thermostat and check the fan clutch? But I have read that others have spent a lot of time & $ chasing this issue without much results.

What else? I don’t think the car nails much, it starts readily when cold. I understand that perfectly balanced flow, clean, correctly operating injectors area ideal. I plan to do a diesel purge. And, of course, keep good oil in it.

But, I am thinking that it is just not necessary to pull the injectors, which will "change" stresses in the head if there are no apparent injector problems? If it ain’t broke, don’t fix it?

What else can be done to keep this engine running strongly and preserve the good 14 head?

Diseasel300 · #2 12-22-2018, 12:06 PM

The cooling system is the most important part to keep up to snuff. Nothing else really matters, if the head is going to crack, it's going to crack. Whether or not those cracks lead to compression leaks or oil/coolant consumption is luck of the draw. I personally think the paranoia behind the 14 head is overblown.

The hunting temps are probably due to thermostat problems or fan clutch as you mentioned. Mine hunted would drift up to 100-105 in hot weather with A/C or slow traffic until I changed the fan clutch. Swap over to the 606 turbo clutch and 11 blade fan, it helps the A/C and helps airflow over the radiator.

sixto · #3 12-22-2018, 12:48 PM

The injectors thread into the prechambers, not directly into the head. If it’s running nicely, don’t mess with the injectors.

Doesn’t nail much? It shouldn’t nail at all! Maybe you hear the effects of a lazy glow plug after a cold start. Afterglow is wonderful.

If your consicience allows consider umm... limiting EGR flow to the intake manifold. It can’t hurt the head to limit what the combustion chambers get to clean air and clean fuel. Make sure blow by and oil leaks into the turbo are in check.

Sixto
98 E320s sedan and wagon
02 C320 wagon

bsmuwk · #4 12-22-2018, 12:57 PM

Even if the 14 cracks, if your machinist knows what he's doing they can be welded. I do it all the time and there are members on this forum that are driving around with my welded heads for years.

For what it's worth, it's not a matter of preservation - the head WILL crack and has most likely already started. The expansion tank cap in PROPER working order and preventing overheating will postpone your head removal. I think the lowest mileage 603 I've pulled apart had 27k on it, and it was already cracking at the prechamber.

jake12tech · #5 12-22-2018, 01:22 PM

Don’t overheat it.

robertb1958 · #6 12-22-2018, 01:26 PM

Sixto - without reference or experience, it is hard for me to know the difference between typical diesel sound and excessive nailing.

The wagon had a little pinging, especially when cold. I took it on a 150 mi trip that I was late (and thereby a little lead footed) to, it ran better (quieter) after.

The sedan seems to have a little more "clatter" sound than the wagon. It's stronger, for sure, wonder if the ALDA has been tweaked. Will have to inspect.

The wagon has a BB in the line to the EGR. Glad you reminded me, I need to do the same to the sedan.

Thanks for the info to all so far.

97 SL320 · #7 12-22-2018, 02:53 PM

Quote:

Originally Posted by robertb1958

Obviously, keeping the cooling system in good shape will help. The wagon I have runs just above 80, dead steady even in the summer with AC. The sedan temp floats between 80 and a little below 100, even in cold weather and with heat on the highway. Sort of tempting to change the thermostat and check the fan clutch? But I have read that others have spent a lot of time & $ chasing this issue without much results.

Thermal swings are hard on cylinder heads.

Change the thermostat, the plunger is sticking. Or maybe this occurred. Look at my post 5 here 1995 e320 running hot

Fans don't do much above 35 MPH and given it is fine in hot weather, leave it alone.

Also make sure the pressure cap is in good condition. System pressure is critical to prevent boiling in the cylinder head. You will never see this boiling because the bubbles mostly condense before making their way to the rad and you are not looking at the system when the engine is under load.

vstech · #8 12-22-2018, 06:38 PM

Above all else, make sure your serpentine belt systems are looked after.
The alternator will cause belt tensioner chatter, and allow a loose belt, or damage the spring or shock.

It isnt the cooling system that kills the head... it is driving after the belt breaks... ANY distance.
Sure, clean radiator, working fan, and water pump are ideal to keep engine temps stable, but driving with a coolant leak, or a broken belt are the death nails for the head.

sixto · #9 12-22-2018, 09:37 PM

Quote:

Originally Posted by robertb1958

Sixto - without reference or experience, it is hard for me to know the difference between typical diesel sound and excessive nailing.

Nailing is a painful sound like pounding a nail into concrete. It’s rarely rhythmic. Clatter at any volume can be pleasant to the Diesel purist

Sixto
98 E320s sedan and wagon
02 C320 wagon

ah-kay · #10 12-22-2018, 10:08 PM

There is nothing special to run an OM603 engine. Make sure the temperature is normal, serpentine belt is tight, aux fan resister is not burnt out, the thermostat cut-in switch is working as expected. That's about it. The problem with#14 head is really overblown IMHO.

sixto · #11 12-22-2018, 10:24 PM

You’re saying the #14 casting’s everything it’s cracked up to be?

Sixto
98 E320s sedan and wagon
02 C320 wagon

ah-kay · #12 12-23-2018, 01:16 AM

Quote:

Originally Posted by sixto

You’re saying the #14 casting’s everything it’s cracked up to be?

Sixto
98 E320s sedan and wagon
02 C320 wagon

Yes. Overblown issue.

ah-kay · #13 12-23-2018, 01:18 AM

Quote:

Originally Posted by Diseasel300

I personally think the paranoia behind the 14 head is overblown.

.

X2

Diseasel300 · #14 12-23-2018, 10:30 AM

Quote:

Originally Posted by bsmuwk

For what it's worth, it's not a matter of preservation - the head WILL crack and has most likely already started. I think the lowest mileage 603 I've pulled apart had 27k on it, and it was already cracking at the prechamber.

Again, a pretty broad/sweeping generalization that's pretty unfair. Why would the head come off a 27K mile car unless there were problems? If it cracked that early (and that's why the head was coming off?), it would indicate a manufacturing defect, not a design fault.

The head came off my SDL for valve work at 173K on the odo (no idea what the actual mileage was since the odo had stopped) and had zero cracks, zero warpage, and still had the factory head gasket fitted.

They can last if looked after. Sure the later castings are stronger, but there are enough 14 heads out there running that says they're better than people like to think they are.

barry12345 · #15 12-23-2018, 11:32 AM

A few things I have observed over time. Control of the alloy used in casting may have ben poor. One member did several hardness tests some years back. The tests showed a substantial difference in Rockwell hardness numbers. Between 603 heads.

Plus most have used these engines like non turbo gas engines. Letting them run a minute or so before shutting down does tend to equalize hot spots. The coefficient of expansion and contraction is substantially greater than with cast iron. So if hot spots boil off the stresses will be substantionaly more and over time can take their toll. .

Also there is the turbo bearing and seals to consider. As soon as you shut down the cooling effect of the oil flow is lost. Some of the latest Volkswagon gas cars have added an electric oil pump that cycles on for a minute when you shut the engine down. To service the turbo and bearings by absorbing heat.

If people persist in not observing the requirements of tubo engines from an operational standpoint. Especially those with lets say inherent weakness issues. There is a price to pay in longevity. This also is a good practice with even the all cast iron engines.

It is a hard habit to develop. Plus there is no certainty. At the same time leaving the engine at idle before shutting down is not going to hurt anything. Especially after a highway run.

Driving up to a fuel pump when just pulling off the highways. Shutting down right away to refuel is perhaps about as abusive of a diesel engine as possible. Instead hang back and let the engine idle for a minute of two before pulling up to the the fuel pumps and shutting down to refuel.

For the cost of the additive a water wetter agent might also be considered. Every attempt to prolong may be a failure at the same time. As these engines do not even appear to like moderately high operational tempertures. This to me also is an indication that hot spots may be boiling off during normal operation. As was mentioned by an earlier poster.

If this is the case another contributor is. Test your rad cap for its release pressure. A low pressure cooling system just might have a little influence on those hot spots. Higher coolant pressure may reduce the extent of boiling off hot spots to some degree. Again this is something that is far from certain.

There are other reasons to not want a tired radiator cap with age. So you can get them tested easy enough. If I did not have a pressure tester I can see a garage doing this for me for free. Or a rad shop. It may be fine but untested there is no assurance it is. You just take your radiator cap in.