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Old 10-17-2000, 11:42 PM
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Gentlemen I have 3 questions regarding my belowed '86 300E. First: since the weather is geting colder I have noticed that my coolant temparutere is down to about 80 degrees or even a bit below at highway speeds. This did not happen in previous years I am wondering if it is the thermostat (I put in a brand new from Benz 3 years ago). The courious thing however is that the car seems to be running hotter in town as well (fans are ok so is the fanclutch and fuses). Go figure, by the way milage is about 260K. Second: Engine never been touched. It is burning oil. Approx. 3 quarts per 3000 miles. Does not smoke not even at startup. Passed emission test 3 months ago. According to my mechanic (only repairs Benzes and Bimmers (I know the heretic :-) ) it is time to replace the valve guides and seals, quoted me about $800.00 US for pulling the head, machining it etc. Said the bottom end namely pistons and rings should not need to be touched 'cause they are very strong. Is he right?
Third: I would like to get the lowdown on the exact procedure on flushing the cooling system. I do have the shopmanual but not much info there. I drained the coolant from the rad but only about 3/4 gallon came out and I even took out the bolt on the top of the engine (probably a bleeding hole?) plus the bolt on the top of the thermostat housing (of course opened up the coolant expansion tank). Coolant was ugly, bit rusty too in colour, it was changed two years ago. So what do I miss here? Is there a bleeding bolt at the bottom of the engine as well? Thanks for your help in advance.

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Old 10-18-2000, 08:48 AM
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Insteresting pheneomena. Very cool at high speeds and very hot at idle. I wonder if you have a temp. sensor / guage problem.

Your rad probably has around 2-4 galls of water I would assume so you did not get it all out (unless you were running very low and you did not know it). When you replenish the liquids, put in the recommended 50-50 mix (water / antifreeze). Also, when you are running the car from a cold start, maybe touch both the coolant supply and return hoses and see if they are heating at the same time. This may inform you that you have a clogged radiator.

I doubt that is is yout thermostat after just a couple of years, but you never know. It would not hurt to replace that if all else fails.

The $800 seems stiff for that much work, but you may be talking about Canadien and not $US, in that case, fairly reasonable.

'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)
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Old 10-18-2000, 08:55 AM
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Just had the valve seals replaced and total cost was in the range of $375. The mb mechanic did not the pull the head to do the job. It immediately cured the problem and I'm back to getting an oil change to last the full 3,000 miles w/o adding any additional oil.

Jerry O
1987 260E 175k miles
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Old 10-18-2000, 11:23 AM
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Join Date: Jul 1999
Location: CT, USA
Posts: 2,699
$800 US seems like a good price for that job...up here in New England it usually runs $1k or better.

I understand that the guides & seals can be replaced without taking the head off, but isn't an upgraded head gasket the reason most people elect to go for the more involved head job?? Just curious...

All the best, Michael
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Old 10-18-2000, 07:15 PM
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Location: New Bedford, MA USA
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Head has to come off for guides to be pressed out and replaced. There is a drain plug in the radiator, left lower corner facing the car. Believe it's red in color. Cool on the highway with a low ambient temp is not abnormal. If it's hot in traffic, even with low ambient, start looking at the t-stat, have the radiator flushed when you are having the head done. If the coolant was rusty as you describe, have the tech check the water jacket openings in the deck when the head is off, you may have to really flush all that crap out. if you remove the t-stat, take a look at it, if it's gummy and full of crud, then, it's probably kaput.

Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
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Old 10-18-2000, 08:44 PM
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Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
There is also a block drain below the rear exhaust manifold. It is a 19mm bolt.

The price is gooooood on that valve job, we quote $1200to 1,500. We use all factory parts though.

Donnie Drummonds
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Old 10-18-2000, 09:06 PM
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dacia: I've notice that my 91 300E is also running cool on the highway... 80 degrees, and alittle hotter in the city. I drove back from T.O. last night doing 150Km/h most of the way and I expected the temp to be higher as I've noticed on a number of occasions in the past. (I've had the car for 3 weeks) I attributed the reading to the lower air temp... I think the digital temp display said 3 dergrees. I'm not the least bit worried.
Just my $0.02

Cheers for now.
91 300E

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Old 10-18-2000, 10:30 PM
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Thanks guys for all the info I will consult with my friend regarding the temp issue he has an '88 300E, as to the coolant drainig procedure I will figure out something over the wekend, and will change the thermostat just in case (and check the opening temperature on it). Thanks again

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