I changed my radiator and thermostat yesterday. The thermo housing (thermo gasket) and radiator had both been leaking

Obvoiusly I drained all the coolant from the radiator, but I did not do a full flush because I haven't been having any problems with overheating. I did cyphon some of the coolant from below the thermo, but did not pull the coolant plug on the engine... not sure how much I drained, but it seemed like a couple gallons total in the bin.

Filled up the radiator with coolant today, burped the upper hose by squeezing it to make sure I was getting it as full as possible from the top. In total, I got about 2 gallons in, just under...

Went out and drove it - all seemed ok, holding steady at just above 175° F.

Then stopped at a rummage sale, got back in the car, and when I started it, the temp read close to the next mark, which is 212° I believe (halfway between 175 and 250). It dropped quicky though once the car was running (within 20 seconds)

Since that, it has been running a little warm, like halfway between the 175 and next, unlabeled mark. (running maybe around 190°?). The heater does drop the temp somewhat, but not all the way to normal.

Also, upper radiator hose seems bulgier than I remember them being in the past... but don't know if I have taken that much note before...

It feels hot to the touch. Lower one is not bulging and feels normal room/air temp (not hot or cold).

The radiator cap has not vented anything (dry where it lets out).

What would cause the temp to go up when it is not running?

And Is a bulging upper radiator hose normal?

Pic:


and on the engine side:

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It really is a shame you did not flush it. Especially since you already did a lot of the work? Whatever...

It sounds like you still have some air in the system or the cap is leaking (not holding pressure). Did you use 50/50 coolant and distilled water or straight coolant? Just to clarify.

What were your operating temps. and conditions before the swap?

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AJ

1985 300D (SOLD)

the engine kinda heat soaks after you shut it off. normal. your new t-stat may open a bit later than the old one. not a big deal either. the bulging hose if its old means its weak and should be replaced. if its new, might just be a tad different size than the old one. the upper hose should feel hot and the lower should be way cooler if the system is working correctly. one more thing, your radiator cap may not have sealed as good on the old radiator. it is designed to vent excess pressure if there is any. might be working correctly now, although i have seen a very few that failed in that they would not vent excess pressure correctly. sounds like get a new hose and cap if they're old, and just keep an eye on the gauge.

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1984 300TD "MAX" 303K+ still going...
fast '70 Chevelle 200k+
home built Shovelhead chopper

Yes, 50/50 coolant/water.

Sorry, should have mentioned - hoses are both brand new. Replaced those with the swap.

If the system was not holding pressure/leaky cap, then why would the hose bulge? Wouldn't it be the opposite?

The cap is old, should have gotten a new one when I ordered the radiator but forgot. I know it DID vent on the old radiator because I would occasionally see drips/wetness at the end of the vent hose.

Op temp before was pretty much just above 175° most of the time (maybe 180-185). Seems slightly warmer now (was running about that until my first stop/restart when it got hotter).

Can't say much about not flushing it other than I have a dirt/weeds driveway with these prickly thorn ball things that stick into everything and pop bike tires and rolling around under the car at the moment is not the most wonderful adventure. I would like to do it some time when I have a more desirable surface to get horizontal on.

Oh, one question - under what circumstances is it safe to open the radiator cap after it has been running?

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Maybe it has something to do with the fact that the water pump stops pumping and the coolant stops circulating.

You've read my user title haven't you?

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sounds like you really have nothing to worry about. if the cap won't vent, pressure will go too high, but i think your new hose is just a bit different from the old hose, and your new t-stat just opens later. relax, you did a good job even w/out the flush. if the old coolant wasn't nasty dirty and acidic, worry about it next year.

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1984 300TD "MAX" 303K+ still going...
fast '70 Chevelle 200k+
home built Shovelhead chopper

Why are you giving temp readouts in Fahrenheit?

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

he must have a 79 cluster in there...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Yea, sorry about that... my 79 has a 79 cluster in it...

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Interesting...I didn't realize they made a car with "F"! Good to know.

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1987 300TDT - 195,000 (Original #14 head)
1993 190E 2.3 - 105,000
1981 300D - 250,000

The one year it made sense!

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AJ

1985 300D (SOLD)

You would think they could have wrote both the degree C and F numbers on the same gauge like they do with with some Speedometers I have seen that have mph and kmh on them.

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84 300D, 82 Volvo 244Gl Diesel

Found this thread & put my mind to ease, thanks for the post!

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