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Too Much Pressure In Cooling System


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#1 victorludorum

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Posted 05 June 2019 - 10:19 AM

I have a year 2000 mpi. One of the thermostat gaskets blew recently, and after replacing them with some difficulty (tiny leaks), they are now leak free. What I am getting now though is steam escaping from the expansion tank cap, which suggests that there is another problem at the root of all of this. I haven't taken the rocker cover off yet, but there's no water in the engine oil, so I'm not sure it's a head gasket problem.

 

Does anyone have any ideas at this point? Cheers all :-)



#2 mini13

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Posted 05 June 2019 - 10:36 AM

rather than too much pressure it could just be the cap is getting leaky, is there any exhaust smell to the coolant?



#3 victorludorum

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Posted 05 June 2019 - 12:03 PM

Well it's only water in there at the moment as I've had to empty the system a few times and water is constantly escaping. How would you describe and 'exhaust' small?



#4 victorludorum

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Posted 05 June 2019 - 12:04 PM

I guess I'm leaning towards there being too much pressure because of the blown gasket.



#5 Fast Ivan

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Posted 05 June 2019 - 12:11 PM

the MPI coolant system operates at a high pressure, so don't blame the head gasket just yet

 

as suggested - replace the expansion cap, this is quite a common problem, and go from there

There are varying qualities though so maybe get a couple and have a google search for recommendations 



#6 nicklouse

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Posted 05 June 2019 - 12:27 PM

I guess I'm leaning towards there being too much pressure because of the blown gasket.

then do a compression test. if that is inconclusive, with a cold engine remove the expansion cap and start the engine. what happens?



#7 victorludorum

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Posted 05 June 2019 - 12:44 PM

When I say blown gasket, I mean the thermostat gasket.



#8 mini13

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Posted 05 June 2019 - 12:48 PM

if youve got combustion gasses getting into the cooling system from a dodge headgasket or cracked head, you usually get some kind of combustion residue and the coolant goes darker and smells fuely/ exhausty, often with an oil film on top.



#9 victorludorum

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Posted 05 June 2019 - 01:33 PM

if youve got combustion gasses getting into the cooling system from a dodge headgasket or cracked head, you usually get some kind of combustion residue and the coolant goes darker and smells fuely/ exhausty, often with an oil film on top.

It doesn't have that. The problem I have is that it's my wife's car, and the information I'm getting from her about 'what happened' is a bit blurred. I'm going to take it out for a run myself when the rain stops to see what's happening. I've only seen it when she pulled in last night and there was steam coming from the cap. She said that she added some water, so it could be that she didn't put the cap back on properly, but it was too hot last night to try it.



#10 viz139

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Posted 05 June 2019 - 10:12 PM

There is a small hose outlet close to the cap, they are known to crack and release steam in the same area,



#11 victorludorum

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Posted 06 June 2019 - 12:52 PM

I just ran it for about 20 mins. Got it up to normal temp and drove it (in town) for about 10 mins after with no overheating. When I pulled up and stopped the engine I could hear bubbling in the overflow tank and water overflowing from the cap. Before I go and order a new one, is there anything else that this might be?



#12 Fast Ivan

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Posted 06 June 2019 - 01:14 PM

Before I go and order a new one, is there anything else that this might be?

 

It's the most likely culprit and its cheap, replace and go from there  



#13 victorludorum

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Posted 06 June 2019 - 03:39 PM

Ordered... and fingers crossed that that's it.

 

Cheers for all the input chaps, it's very much appreciated :-)



#14 Chris M

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Posted 30 June 2019 - 08:15 PM

Hi did you fix this problem as I have exactly the same problem & suspect it’s the head gasket.

#15 pete l

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Posted 01 July 2019 - 08:24 AM

There are some really bad expansion caps out there. Try and get a genuine one.






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