overheating

ve2dict · 12-13-2008, 04:28 PM

im thinking headgasket

just bought an mk 1 supposedly just had a thermostat, no leaks, ran fine but cruising in 5th at like 3000 suddenly temp jumped to buried....then a few secs later went back down to normal then up then down....so i was thinking ok it cant be fluctuating that much so quickly so it must not be reading properly....then a coolant line blew off so apparently it was indeed over heating.waited for it to cool down , reaatached hose filled...this time opened front bleed not knowing if previos owner did ( this is on drive home from buying car 45 min drive) and drove the last 10 min with no problems

so i let idle for an hour when i got home ....no over heating....so either intermitent head gasket or air pocket , what do u think?

maybe best bet would be replace hg, remove thermostat, replace coolant temp sensor and bleed system

CyFi · 12-13-2008, 04:37 PM

Head gaskets aren't really intermittent. You probably just had air in the system, a coolant flush wouldn't hurt at all either, along with proper bleeding, then go from there.

ve2dict · 12-13-2008, 04:43 PM

yeah hg's usually arnt interm but one i previously had i bleed and bleed and replaced everything but the hg and sure enough after a month of it overheating maybe once a week i replaced the hg and it was good to go

CyFi · 12-13-2008, 06:39 PM

If you really think that is the problem, do a leak down test with the rad cap off and as you pressurize each cylinder watch for the level of the coolant rising/bubbling

ve2dict · 12-13-2008, 06:53 PM

if it dosnt act up but when its at high temps though leak down might not work

CyFi · 12-13-2008, 08:32 PM

Why would it only leak at high temperatures? You could also do a leak down with the engine warm if you want.

ve2dict · 12-13-2008, 08:35 PM

i suppose i could.....it could only leak at higher temps because stuff expands at higher temps

CyFi · 12-13-2008, 08:40 PM

You can also go to napa and get a block tester kit that tests for combustion gasses in the coolant

ve2dict · 12-13-2008, 09:56 PM

hmm interesting never heard of such a thing....does it test like left over...like the gases were in there and it can tell even though maybe its not acting up at the time

CyFi · 12-14-2008, 04:36 PM

its just a liquid container that you put a special liquid into and you put it over the radiator cap with the engine running and suck air through the liquid (from inside the cooling system) and if it contains any hydrocarbons or combustion gasses it changes color. If you have access to a exhaust gas analyzer you can hold the probe right above the coolant in the radiator and check that way too.

In most cases a head gasket is either blown or not, expansion and contraction of the metal really isn't going to make a difference. Even if it did it would be slight, and if anything i would think it would act up more when its cold than any other time. If you have an automatic trans you can have someone load the engine while you are doing the test to try to raise cylinder pressure.

ve2dict · 12-29-2008, 06:43 PM

replaced head gasket. intermitent overheating problem gone.

Maticuno · 01-04-2009, 08:45 PM

Did you do the job yourself or did you have it done somewhere? How many miles are on the clock?

12-13-2008, 04:28 PM	#1 (permalink)
ve2dict Cage Fighter Join Date: Nov 2008 Posts: 121 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	overheating im thinking headgasket just bought an mk 1 supposedly just had a thermostat, no leaks, ran fine but cruising in 5th at like 3000 suddenly temp jumped to buried....then a few secs later went back down to normal then up then down....so i was thinking ok it cant be fluctuating that much so quickly so it must not be reading properly....then a coolant line blew off so apparently it was indeed over heating.waited for it to cool down , reaatached hose filled...this time opened front bleed not knowing if previos owner did ( this is on drive home from buying car 45 min drive) and drove the last 10 min with no problems so i let idle for an hour when i got home ....no over heating....so either intermitent head gasket or air pocket , what do u think? maybe best bet would be replace hg, remove thermostat, replace coolant temp sensor and bleed system

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12-13-2008, 04:37 PM	#2 (permalink)
CyFi Moved on Join Date: Oct 2005 Location: Phoenix Posts: 1,401 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (11/100% )	Head gaskets aren't really intermittent. You probably just had air in the system, a coolant flush wouldn't hurt at all either, along with proper bleeding, then go from there.

12-13-2008, 04:43 PM	#3 (permalink)
ve2dict Cage Fighter Join Date: Nov 2008 Posts: 121 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	yeah hg's usually arnt interm but one i previously had i bleed and bleed and replaced everything but the hg and sure enough after a month of it overheating maybe once a week i replaced the hg and it was good to go

12-13-2008, 06:39 PM	#4 (permalink)
CyFi Moved on Join Date: Oct 2005 Location: Phoenix Posts: 1,401 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (11/100% )	If you really think that is the problem, do a leak down test with the rad cap off and as you pressurize each cylinder watch for the level of the coolant rising/bubbling

12-13-2008, 06:53 PM	#5 (permalink)
ve2dict Cage Fighter Join Date: Nov 2008 Posts: 121 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	if it dosnt act up but when its at high temps though leak down might not work

12-13-2008, 08:32 PM	#6 (permalink)
CyFi Moved on Join Date: Oct 2005 Location: Phoenix Posts: 1,401 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (11/100% )	Why would it only leak at high temperatures? You could also do a leak down with the engine warm if you want.

12-13-2008, 08:35 PM	#7 (permalink)
ve2dict Cage Fighter Join Date: Nov 2008 Posts: 121 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	i suppose i could.....it could only leak at higher temps because stuff expands at higher temps

12-13-2008, 08:40 PM	#8 (permalink)
CyFi Moved on Join Date: Oct 2005 Location: Phoenix Posts: 1,401 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (11/100% )	You can also go to napa and get a block tester kit that tests for combustion gasses in the coolant

12-13-2008, 09:56 PM	#9 (permalink)
ve2dict Cage Fighter Join Date: Nov 2008 Posts: 121 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	hmm interesting never heard of such a thing....does it test like left over...like the gases were in there and it can tell even though maybe its not acting up at the time

12-14-2008, 04:36 PM	#10 (permalink)
CyFi Moved on Join Date: Oct 2005 Location: Phoenix Posts: 1,401 Thanks: 12 Thanked 38 Times in 35 Posts iTrader Rating: (11/100% )	its just a liquid container that you put a special liquid into and you put it over the radiator cap with the engine running and suck air through the liquid (from inside the cooling system) and if it contains any hydrocarbons or combustion gasses it changes color. If you have access to a exhaust gas analyzer you can hold the probe right above the coolant in the radiator and check that way too. In most cases a head gasket is either blown or not, expansion and contraction of the metal really isn't going to make a difference. Even if it did it would be slight, and if anything i would think it would act up more when its cold than any other time. If you have an automatic trans you can have someone load the engine while you are doing the test to try to raise cylinder pressure.

12-29-2008, 06:43 PM	#11 (permalink)
ve2dict Cage Fighter Join Date: Nov 2008 Posts: 121 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	replaced head gasket. intermitent overheating problem gone.

01-04-2009, 08:45 PM	#12 (permalink)
Maticuno Park Ranging Join Date: Aug 2008 Location: California Deserts Posts: 313 Thanks: 15 Thanked 25 Times in 17 Posts iTrader Rating: (2/100% )	Did you do the job yourself or did you have it done somewhere? How many miles are on the clock?