How's my head??? - PeachParts Mercedes-Benz Forum

JHZR2 · #1 07-21-2002, 03:01 PM

Hi,

I have noticed a few oily spots on and under my 83 300D lately, such as the hoses going to and from the cooler to the side of the radiator, and around the valve cover. At the back side of my engine, the valve cover gasket looks oily, but the area by the prechamber, where the head gasket is is quite wet with oil.

Today I decided to add some water wetter to my antifreeze today, as I drive 40 mile trips at 75mph in 90+ heat, and the engine temp often creeps to right around 100C. WHen I opened my radiator coolant bottle cap, much to my suprise, I saw what looked like tiny specks of oil floating on top fo my coolant. Not a lot, just a litte bit, but I think it must have been oil. The only odd thing is that the oil looked clean, i.e. light brown, rather then black which is the color of my oil after 5 minutes of being in my car.

Are little floating droplets of something or other common? Is this hinting that my head gasket is going to fail anytime now? If oil does get into the coolant, and its black diesel oil, do the drops usually stay black, or does the particulate mess go away, so only light colored oil wil be seen floating? Also, what color is real MB anti freeze mixture when in the car? I pipetted a bit out to observe, and it was a dingy orange color, translucent at best, is this right?

I know that since I changed my oil last, about 2K miles ago, I had the oil level go from around the top notch on the dipstick to right around the bottom. This is more oil use that I usually see, but I attributed it ot the fact that I have een driving fast in high heats, operating at 75+ mph with AC on at over 90 out and 100C operating temp.

Any ideas? Thanks

JMH

The Warden · #2 07-21-2002, 04:06 PM

Offhand, I'd guess your head gasket's okay. However, the coolant sounds like it's pretty dirty. I'd suggest changing the coolant out and flushing the system. Those light brown droplets almost sound like rust particles, and the coolant itself soundslike it's real rusty...

Just a thought...good luck! I've heard on this site that using citric acid is a good idea when flushing the system out.

JHZR2 · #3 07-21-2002, 04:11 PM

the only thing is that I had my coolant flushed and replaced at the dealer ~3 months and 10K miles ago... Maybe the system overall is just so dirty it could use it again... But they definitely look like tiny oil droplets in there...

The thing is, there is definitely an oil leak overboard towards the back side of my engine. After tracing it I see that it comes down and drips off the bottom of the transmission (the round thing that drops down between the oil pan and the pan farther back that id assume is the trans oil). If it is the valve gasket dripping down, ok then Ive solved it, but perhaps it is the head gasket and it is rotting towards the back?

Thanks

JMH

lrg · #4 07-22-2002, 02:05 AM

My guess is it's the head gasket. If you hadn't just had it flushed I'd maybe think otherwise. While oil and water don't mix, often times if you agitate oil in a hot water solution the oil gets a chocolate milk looking brown color. My biggest concern is if you are getting water/coolant in your oil. Does the oil look clean? If it's really bad you'll see it on your dipstick other wise you'll need to drain the oil out. Coolant in your oil will quickly ruin your engine so at minimum check this out. Also, a decent radiator shop or mechanic can check your exhaust for signs of coolant. If the oil and exhaust check out OK then you may be able to get away without an immediate repair but beware that the head gasket could giveout further and cause much bigger problems down the road. Good luck and let us know what happens.

The Warden · #5 07-22-2002, 04:07 AM

Quote:

Originally posted by lrg
Also, a decent radiator shop or mechanic can check your exhaust for signs of coolant.

If you were getting coolant into the combustion chambers, wouldn't the car be seriously smoking white?

I ask 'cause I'm a bit concerned about my 300D's engine. The exhaust has an almost sweet smell (no unusual smoke out the exhaust, though), and I'm getting quite a bit of blow-by (as you may have seen me mention before). However, I have yet to see the coolant level go down or the coolant look dirty, and a compression check done by TXBill on here turned up good results.

The oil looks normal too (also, comsumption is very low; don't think I've used more than a quart so far, and I've driven the car a good 3000 miles since picking it up in Dallas; also, pressure looks good), although I need to change it (will do so after I'm done moving; also need to put some SeaFoam in the crankcase). I'm happy to admit that the car drives beautifully; were it not for the exhaust smell and the blow-by, I'd say everything's perfect...this is one of those issues where, while the smell's annoying, I can definitely live with it as long as I know the engine's okay...the compression test results made me happy, but I'm still wondering...one of those quiet nagging doubts, know what I mean?

engatwork · #6 07-22-2002, 06:47 AM

JMH - it sounds like it may be time to pull the head and see what is going on. You can drive it like this but it will just get worse.

JHZR2 · #7 07-22-2002, 09:05 AM

the other odd thing, though, is that I do not use any coolant, no traces of it in the exhaust, and no smoke... Its like a one-way thing...
Im definitely going to get the head looked at, how long will a head gasket last anyway? Id guess its the original, soits nearly 20 yrs old. I wonder if using synthetic rotella caused the oil to diffuse through the gasket into the coolant, but kept it from going the other way.

Also, if I got the head gasket done, is it advisable to get a valve job done too, where I get the valves reground and seats replaced, or is this unnecessary? I need a valve adjustment, but maybe the valves themselves could use some work...

Thanks for all the help, I really appreciate it.

JMH

engatwork · #8 07-22-2002, 10:35 AM

Most definitely - go through the head while it is off - seals and guides if necessary. This will also give you a good opportunity to see what kind of condition the cylinders are in. Hopefully, you will still see some cross hatching. Go ahead and replace the chain guides while you are in there.

JHZR2 · #9 07-22-2002, 11:22 AM

I called my local MB dealer, and they said to get the head off and grind the valves, etc, it would cost me in the ballpark of $3-3500! Now thats more then I paid for the car, and Im not so sure I want to go that way... I can reflush the coolant over and over, and replace oil more often for a LONG while for $3500.

Does anyone have an idea what they have paid for head jobs? Im calling the local european independent, theyll give me a price as well. I was hoping maybe $1000-1500 or so (my mothers plymouth costed $800 for a 4cyl head gasket and all belts replaced at the dealer).

Also, would someone mind running down with me the signs of a bad head gasket? Also, give me a little discription of what good, clean MB antifreeze should look like?

Finally, is the radiator ONLY for engine coolant, or is some of the capacity in it, the bottom perhaps, for example, used to cool oil, ATF, etc? I know I read one time that some radiators have a section in the bottom for cooling other fluids.

Many thanks

JMH