I thought I should post this over here too.

Today I was driving from Tampa to Lakeland, about 35 miles. With about 12 miles to go my car was rapidly approaching the 120º mark. I pulled off the highway and shut her down. Was feeling around to see what was hot. NOT the radiator or any of the tanks on the side of the radiator. Hummm, the thermostat must be stuck. By the way, it has always ran hot since I got it. Let it cool down some and then limped to Lakeland. Got into the neighborhood, shut it down and costed to the house.

I was going to finally fix my broken tranny dipstick but my cooling system seemed to beg more attention. Took the thermostat out and began to flush the system. WOAH, did the radiator seem to need a LOT of pressure to get water to run through it. Connected the garden house to the upper radiator hose to the radiator and then let it run through the radiator then through the block and out where the upper radiator hose would be connected. Let this go on while I ate dinner. Then I closed everything up and put SHOUT cleaning gel in it to degrease the system. Ran it and drove it for a while with the t-stat out. Drained it, flushed it, then put in water and Prestone Citrus Flush. The directions say you can leave it in your system for three days so I also put the t-stat back in and drove her around. When I was driving around it is just a hair over 80º. At stop lights it approaches the 100º mark but never hits it and quickly climbs back down as I get moving again, what an improvement! I will leave the citrus flush in over night and then put anti-freeze back in tomorrow.

Looks like my t-stat is fine and I am already much happier with the temperatures I am getting now. Like night and day difference. My radiator must have been really plugged up as the radiator gets warm and the tank on the upper radiator hose side gets hot now. I am now seeing how important it is to maintain a coolant system, at least if you plan to have the car over two decades.

I hope I didn't do any damage to my head, man these aluminum heads freak me out!

Are you draining out the radiator only or out the block drain as well?

Sixto
87 300D

I was trying to drain both by having the t-stat removed and using the lower radiator hose. Which seemed to be working pretty well.

When I got started the sun was going down and I did not see a block drain plug. Admittedly, I did not search that much. On my OM616 it is easy to see and pretty easy to get to.

drain plug on passenger side of engine, has a hex head with a nipple for a drain hose.

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You might drain the coolant into a clean container then pull the radiator for a good cleaning of the outside fins, then send water through the condenser from the engine side.

There's a school of though that radiators are 5-10 year replacement items; leaks, cracks or not.

Sixto
87 300D

Theres no coolant in it now so I could still do that tomorrow. But the Transmission lines never seem to want to come off and it did not seem like an airflow problem but a coolant flow problem.

I do not like that school of thought

Thank you

Just an update. Made the Lakeland-Tampa drive today and never touched the 100 degree mark. Looks like I have it sorted out and I'm pretty happy with the results.

I'd expect it to be steady between 85* and 90*C with no traffic, hills or driving above 90 mph. Is that what you saw?

Sixto
87 300D

prestone flush is good but so is citric acid from the grocery store - cheap to boot too.

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Well I spoke to soon. Got back in my car to head to the PNP to get a windshield assembly and three miles down the road someone yells at me asking me if I knew if my motor was going to blow soon. I looked at my instrument cluster and say no. He tells me I have coolant pouring out of my car. Sure enough my low coolant light comes on and my temperature starts rising! I pull over. She puked all her new blue coolant out when the lower radiator hose blew off. I walk to a near by advanced buy a screw driver, new clamp, and coolant. Get back on the road again. Three miles down the road and BANG. I am at a stop light so get out and go have a look. The hose blew off again. Someone on the road helped me push it into a near by CVS. The second time it blew off was because the hose clamp was too big and not on correctly so I used the original clamp again. Filled it with water from CVS and went less than a mile to my work where I got more water for it. This time I filled it and started the car. It started bubbling and the bubbles had what looks to be smoke in it. But I keep going until I reach my apartment and it stayed right at 80 degrees after fixing the hose the second time for the rest of the way home.

My questions:
A) why did the hose blow on a short city trip but not a 10x longer highway trip?
B) do I have a bad head gasket? Or we're the bubbles just bubbles in the system?

More likely a bad head gasket but I don't know the whole story. Air in the cooling system doesn't develop the kind of pressure that'll unseat a radiator hose. If you had posted sooner, I'd have suggested to limp home with the reservoir pressure cap loose. You won't be able to sustain heat load but it won't puke coolant or unseat unclamped hoses.

You might have a bad fan clutch. There's debate about this but theoretically there's less need for the fan at freeway speed than creeping through the city.

Sixto
87 300D

I thought of this too as soon as it blew off the second time.

I crept though the city after the highway trip and it stayed right around 85 and when it the blew the hose off, the first time, it was around 85 too.

Do I need to ask Santa for a head gasket kit and valve job?

First check your pressure cap. It should open at 1.4 bar/20 psi. You can rent at no net cost a cooling system pressure tester from Autozone. The rental program requires that you buy the rental tool, not a tool from shelf stock, and they return your money when you return the tool. The tester allows you to test the cooling system and separately the cap. The cooling system's probably tight if it's blowing off hoses. The bubbles might just be boiling water so next do a compression test. I don't know if run of the mill auto parts places rent out Diesel compression testers that work with your engine. The tester should be good for at least 450 psi.

Sixto
87 300D

oh man that sucks.

how did you refill the cooling system? it's possible you have air in the head, and you are just seeing steam from the hot block/head...
take the upper hose off, and fill the motor there. fill until the radiator starts to seep out coolant. then put the hose back on, and fill the tank, then push the upper hose down and squeeze it repeatedly until the air is all gone. then you have a full head/block.
I REALLY hope you don't need a new head gasket.
I agree, pull the pressure cap off, and test it.

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