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General Information => Troubleshooting => Topic started by: albsure on September 26, 2005, 12:09:37 am
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hi guys, al b frustrated, i need help with my 91 jetta eco diesel
after changing the thermostat, coolant pump, sensor in the bottom tank of the radiator, and the belts, i'm still overheating. i can see it boil up in the round ball type resevoir tank, and then start spitting out of the side of the reservoir. i didn't know that these reserviors were vented or are they not, or do they have blowout plugs for when the pressure is too high. the cooling fans come on only when the AC is on but thats it. did i get a bad thermostat, ok but the fan should still come on. THE ENGINE RUNS GREAT!what do i look at next ? any one have an idea. its hot here all of the time can it run without a thermostat ? HELP :oops: :cry: ALL THOUGHTS ARE APPRECIATED.
THANK YOU
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the reservoir is not vented. The only time coolant should come out is if the car really does overheat. Is the bottle cracked or is the rubber seal on the cap damaged? How far up does the needle on the gauge go before it starts pissing coolant? If you start it up when fairly cold and take the cap off of the reservoir do you get air bubbles coming out?
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:) hi vwmike and thank you for your reply. i'm not sure if it cracked or the seal but its right at the very top left where if you pull off the plastic sheild appears to be 2 deep concave indentations ( vent holes ) ? i'm not sure i will check bottle and seal at 1st light theneedle is just past 1/2 when it starts to gurgle and then it starts to spit.
yes you get some bubbles and the water appears to siphon up and down
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just a guess... but is your fan working? Maybe there is something clogged in the rad.
my rad fan died... and it overheated and coolant boiled out of the engine :(
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hi jtanguay and thank you. the fan only comes on if i turn the AC on.
it does slow the process, but evevtually it starts gurgling and spitting out of the side of the reservoir.
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why don`t you try shorting the wires at the rad thermoswitch, and see if your fan works on the hi speed (since you know your lo speed works when the ac is on)- this will at least eliminate the electrical side as a problem area
next how much pressure do you build up and how quickly- on a cold engine do you get pressure right away, any mixing of oil & coolant- that may be a head gasket issue
finally as someone suggested maybe the rad is plugged, and the coolant doesnt go through the area where the thermoswitch is located- hence the fan doesn`t come on
hope this helps- report back
cheers
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I have installed a bad thermostat in mine (must have been stuck open b/c the engine would never get up to temperature). When mine was running a little too hot, it was a clogged radiator. Replaced the radiator, no problems since.
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hi dieselpete and thank you.i'll try the switch thing as soon as i send this reply.
after running for only a few minutes you can see the siphoning action in the reservoir tank and then a few more minutes it stsrts gurgling and steaming and spitting from the side of the reservoir ball. there is no water in the oil or oil in the water. thats a good thing. i will take off the top hose and take the thermal switch out of the bottom of thr rad and see what kind of flow i get through the rad. the car is not at my house so this will take me about a 1/2 hour and then i will report right back. i'll wait a few minutes before i leave in case you have more input, questions, or suggestions.
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thank you 91 eco i'm going to check for flow and short the wires at the switch right now i will report back shortly
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Does the car overheat if you're moving, or only when it's sitting there. Could also be an airlock in the cooling system. After changing the thermostat, I usually unhook the top hose from the rad and pour coolant into the engine with it, then pour coolant into the rad.
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thank you for the input addautomotive. ok 1st i started it up and pulled the plug at the thermal switch shorted the terminal and the fans came on . then i shut it off removed the top rad hose and the thermal switch and put a garden hose down the rad hose and water seemed to flow nicely.put the hose back on the engine then disconected the hose from the rad stuck the garden hose in and flowed water back the other way. water flowed out of the reservoir ( top off ) i did not get water out of the upper rad i guess because the thermostat closed. if it is working properly.it is new but i have bought bad ones.???? closed everything and started it up i got a few bubbles in the res. pretty much right away. after a few minutes the temp gauge was between 1/2 and 3/4 and it started gurgling and spitting hot water out of what does appear to a vent holeor blowouthole feature in the res. upper and lower rad hoses were both hot and the fans never came on. so what do you guys think could i have gotten a bad thermal switch and a bad thermostat. i dont know :oops: :(
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thank you for the input addautomotive. ok 1st i started it up and pulled the plug at the thermal switch shorted the terminal and the fans came on . then i shut it off removed the top rad hose and the thermal switch and put a garden hose down the rad hose and water seemed to flow nicely.put the hose back on the engine then disconected the hose from the rad stuck the garden hose in and flowed water back the other way. water flowed out of the reservoir ( top off ) i did not get water out of the upper rad i guess because the thermostat closed. if it is working properly.it is new but i have bought bad ones.???? closed everything and started it up i got a few bubbles in the res. pretty much right away. after a few minutes the temp gauge was between 1/2 and 3/4 and it started gurgling and spitting hot water out of what does appear to a vent holeor blowouthole feature in the res. upper and lower rad hoses were both hot and the fans never came on. so what do you guys think could i have gotten a bad thermal switch and a bad thermostat. i dont know :oops: :(
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Question: how did you fill the system? I'm wondering because sometimes if you fill it wrong you can get an air bubble in the bottom of the cooling system that won't allow any coolant flow. To prevent this you always fill the system by removing the top hose from the radiator and filling through there until the coolant spills out, then reconnecting this hose to the radiator.
Also, you might want to remove the hose that comes out the bottom of the top hose connection to the cylinder head at the front, and put a hose in that and see if you get flow out of the radiator. You should. If not then it might be blocked
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welcome back i havn't seen you for a couple of days. i took the top hose off of the engine and filled through the rad. then took off the other end from the rad. and filled to the block. also is the reservoir vented should it be spitting hot water from the res. should i plug the hole?? what are the chances of getting a bad thermal switch and thermostat. should i leave the parts stores alone and just go to the VW dealer and pay the price for oem parts??
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The vent hole in the top of the spherical A2 and later expansion chamber vents out anything that gets by the pressure cap. Your pressure cap should hold approx 20psi before it vents.
That much coolant getting spat out of the top could only be caused by: 1. overheating, boiling coolant, building up steam and pressure. Listen for any boiling coolant, which might continue for a little while after shutting off the engine. Could be caused by a bad thermostat, bad water pump, insufficiently filled system with air pocket impeding circulation, etc.
Or, 2. a blown headgasket, letting pressurized gasses from the combustion chamber bleed into the cooling system while the engine is running. You can check for this by right after a cold start, removing the pressure cap and sealing the hole with your hand and feeling for an immediate pressure build-up. An immediate pressure build-up indicates a blown head gasket.
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thank you all, i' going to check these things out now and i will report back as soonas i'm finished.
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welcome back i havn't seen you for a couple of days. i took the top hose off of the engine and filled through the rad. then took off the other end from the rad. and filled to the block. also is the reservoir vented should it be spitting hot water from the res. should i plug the hole?? what are the chances of getting a bad thermal switch and thermostat. should i leave the parts stores alone and just go to the VW dealer and pay the price for oem parts??
ah, that might be your problem. If you filled through the rad first you would have forced air down into the water pump, where it could not escape because the thermostat is closed. Try filling it by pouring through the top hose into the engine until the coolant pours out of the hose, then reconnecting the hose to the rad.
Re: chances of getting a bad thermostat: pretty good. Happened to me. Almost warped my cylinder head.
Re: should it be spitting hot water from the reservoir: in my opinion no. My vw diesels have never done that. When they overheated, the coolant came out of the cap. But maybe if the cap is not working then the tank will have another relief valve to prevent it from exploding. Probably does.
You said you replaced the water pump right? Because that can cause very quick overheating if it is not functioning properly. The other cause could be a blown head gasket leaking compression into the cooling system. That sometimes happens on these turbo diesels because of the amount of pressure in the cylinders. It is already a very high compression engine, and then you add a turbo....very very high compression...sometimes I wonder about VW engineers. Anyway, good luck with it.
Chris
ps, in very rare cases, and usually only on the old rabbit 1.5 NA diesels, the engine blocks developed cracked water jackets allowing the coolant and the oil to mix. This could sometimes result in the cooling system becoming pressurized since diesel engines operate at positive crankcase pressure (ie, no engine vacuum). But if this was the case with your car, you would see oil in the coolant. Since you don't, the worst it could be would be the head gasket, unless the cylinder head is cracked and compression is leaking in that way, but you will see that when you take the head off (if you end up having to do that)
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thankyou guys, for all of your input and information. at first light i will start going through everything that has been suggested, first of all draining and refilling properly. then the cold start pressure test at the reservoir. then if necessary i'll run the fans by shorting the thermal switch connection and see what happens, before just running out and buying a new one. maybe its not getting hot enough at the switch to kick the fans on. even if it is a head gasket, the motor runs good, for 181000 miles so i think its worth it.
QUESTION: do i need any special tools to do a head gasket? i am fully equipt to work on gassers but this is my first diesel. hopefully it wont come to that. i will report back.thank you again for all of your help.
al b sure
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I didn't notice if anyone mentioned this, so if I'm repeating something, I appologize. Did you happen to see if the ring on the coolant cap is sitting in it's appropriate groove. I once chased what sounds to be the same problem, and it was just the 'o'ring not situated properly in it's groove on the cap. At a quick glance it looked fine, so check it carefully. If the cap is not sealed properly, it will blow the coolant out of it in no tome.
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special tools for headgasket: You'll need the star shaped tool to take the head bolts out. Also will need some sort of puller to take the cam pulley off and something to lock the injection pump and camshaft. You can manufacture tools to do the locking. And pretty much any sturdy puller will take the cam pulley off (so you can reset the timing belt when you put it back on). But you'll really need to get the star headed tool to take out the head bolts. Can't use anything other than the real thing for that
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Quick way to determine blow head gasket or cracked head. COLD ENGINE.
Open up the resivour. Crank the motor up. If you have bubbles, you have a leak into the combustion chamber.
No bubbles, chances are the head gasket is intact