Howdy everyone,

My '85 has an issue where it seems to hold pressure for a long time after it's been shut off. This results in coolant dripping from hose connections long after the car has been shut off.

- Does not seem to drip any coolant whatsoever during operation.
- Hoses in question are new or have been replaced. Clamps tightened.
- Drips dont start for hours after shutdown (unless I take the rad cap off to relieve pressure)

Car runs perfectly otherwise. Just completed an 8k x-country odyssey without an issue.

Ideas or thoughts much appreciated.

Thank you,
dd

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

Expansion tank cap?

Does the pressure built up fast after it is started when the engine is cold?

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

I compared my expansion tank cap (120 mbar) to my 82's. It didnt seem any different in terms of springiness. I swapped them and havent seen a difference (but i havent gotten the car hot with the new cap either.

I need to go to the store right now, let me find out, but i dont think so.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

No significant pressure when the car was at 60C warming up. Just a little 'pfft' upon opening the cap.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

It shouldnt pfft at 60c.
Much as though I hate to suggest, it sounds like the very early stages of a head gasket problem. While its still warming up, check for tiny bubbles in the coolant.

Try running with the cap on loose, just past the notch, not tightened down. Is your coolant in good shape?

You could try torquing your head. You will need to go say 5~10 ftlb more than the recommended torque, that may fix it if you are lucky.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Why do you come to this conclusion? Ill look for the bubbles. I really hope you are wrong The car runs beautifully - burns no oil, starts first crank below zero, and I've had it for 20k miles now.


Ill try that.

Coolant is a few months old; its Zerex G-05 and distilled water 50/50.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I hope I am wrong as well!!!
There arnt many ways pressure can build apart from getting up to temp or leakage in from combustion chamber.
When you release the pressure,what does it smell of?

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

coolant? I havent given it a sniff test. Im assuming diesel exhaust would be what i dont want to smell.

EDIT: letting it sit overnight after it getting it up to 85C driving around town this evening. will check for coolant leaks, exhaust smells etc. in the morning.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

No diesel exhaust smell in coolant. No bubbles.

No leaks since I have replaced the expansion tank cap. Fingers CROSSED.

I have a read a lot now and understand getting it the coolant tank tested for hydrocarbons is the one way to verify whats indeed is or isnt going on.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

You have me intrigued now. If you leave the car for a day or so does the pressure remain? Do you get the pfft after a couple of days?
I would run it for a few weeks with the cap just past the first notch, that is no pressure & see what happens. If it drives well & has no other motor problems best just enjoy it!!!

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

The pressure remains after a day - but just a little bit.

I have yet to leak coolant with the swapped rad cap. Weird.

Anyways, I'll try running it with the rad cap just past the first notch and see what that does.

Next time Im somewhere with a hydrocarbon tester Ill stick in in the coolant reservoir and see what happens...but until then I think Ill just keep enjoying it.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I had a minor leak from a hose overnight and some pressure the next morning. Bahhh. The hoses are soft in the morning, but it's time to dig deeper and do some confirmation.

So I ordered this: http://www.amazon.com/gp/product/B000NPDL76/ref=oss_product

That will tell me for sure what the deal is. I am going to be testing used motors out soon for the 82 so I figured it's a wise investment (enough bug juice for 16 tests are included).

If the head gasket is blown on this car I am going to need some consoling...its runs SO well. As long as the head isn't cracked I can deal....

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I used a UV dye block tested to test for traces of exhaust in the coolant. Basically, you suck in air from the coolant reservoir and if it turns the blue dye green, theres exhaust in the coolant.

I did the test several times and no sign of any exhaust in the coolant whatsoever. :-)

To test the tester, I then took a small puff of air near the running cars exhaust - instant change to green.

So, Im back to square one. Theres still a lot of residual pressure in my system, but my head gasket checks out.

Anyone want to toss in a theory?

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

I was curious if there were any further developments as I have a similar issue...

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1985 300SD 99K

None really....still runs fine, still weeps a bit of coolant.

It still holds some pressure for a while...but all UV dye hydrocarbon tests come back negative for any headgasket issues.

I confirmed another forum members headgasket leak with the same kit, so i know it works.

I still leak coolant from the built up pressure overnight. It seems to have gotten worse with the cold - the lower the ambient temp, the more likely for an overnight coolant leak,

__________________
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car