radiator cap hissing

The radiator cap on my 95 trans sport 3.1 is hissing, and starting to spit out anti freeze. I just bought this van having just 48k miles. Is this van supposed to have dexcool or reg because whats in it is green, but theres orange stains where the anti freeze has sprayed out. Theres new hoses on this thing and a sticker under the hood that says the system was just serviced. Im wondering if they mixed dexcool with reg antifreeze... arghhhhh

This is classic blown head gasket syndrome, these engine are reknown for that....RUn the engine with radiator cap removed....you should see exhaust bubbles popping from the surface of the liquid.
I just wish I were wrong

I just got back form pep boys and Firestone. Pep boys said they checked and the head gasket is OK, but there might be a blockage. It appears that the cooling system was never flushed by the previous owner and kinda gooked up. I took it to Firestone because the dealer i bought it from does all his warranty work there. They did a power flush with some chemicals, and said to come back in a week for another flush because there was so much brown gunk in the system. I looked in the radiator before i took it, and it didnt look like there was any oil mixing with the water.

ok, how do i check if it is a head gasket? It was power flushed by Firestone, and today its spraying all over the engine compartment again. is there any possiblity of the thermostat being stuck? thanks!

ok, how do i check if it is a head gasket? It was power flushed by Firestone, and today its spraying all over the engine compartment again. is there any possiblity of the thermostat being stuck? thanks!

Of course, In similar cases, I have almost always tried to escape the conclusion by simply REMOVING the thermostat and give it a try. (at least I do not pay for another thermostat if it is not the culprit). You can try it too and see what happens: take your time before announcing a win: without a thermostat, it might change the initial behaviour and let you think you solved the problem, but if you do have a blown gasket, signs like spraying will come back anyway, specially after you stop the engine.

There may be several tell tale signs.
- First is what you experience: sporadic heater performance, spraying coolant from radiator.....
- bubbles exiting from the surface of the liquid: remove radiator cap, make sure it is filled to the top, run the engine, have someone in the car rev up the engine in small bursts. Look at the liquid in radiator: bubble should pop up if leak is severe. With small leaks , it is not so obvious: exhaust will enter the cooling only when the engine is under heavy load
- overheating: this is obvious from the steaming coolant, but may show as variations of indication at temperature gauge
- foam in oil: may show as white foam on inner side of oil filling cap, but not necessarily: a leak from combustion chamber to coolant circuit usually means coolant can also enter a cylinder.
- THe spark plug of the cylinder that has the leak may show signs of rust (given the time).
- THE MOST OBVIOUS SIGN – this one is implacable and leaves no room for alternate interpretation- is this test: I use a tire valve SCREWED to a compressed air hose and I apply the tire valve to spark plug holes one after another: air bubbles immediately show from the radiator when the culprit is found. Easy with a 4 banger, but with a cramped V6, more easily said than done.....(you must position the crankshaft so valves are closed but with short start commands, you find easily the place where you feel the air is held in the cylinder).

Thanks, It goes back to Firestone tomorrow to have them check it out.

well a week now... and still they swear its not a head gasket. Today i test drove it after they replaced the Thermostat.. and 2 miles later it was pegging the guage.. and over heating... back it went... and now they swear its the radiator.... thank god this thing is under warranty!

Having a new radiator is not bad at all....and easily done. As I understand, it is under warranty under 3 months used car coverage I suppose, so I'd understand their reluctance even considering they might have to lift the heads, but nevertheless, I'd be more than happy with you if a new radiator settles the case..it did for me (some time ago...)with my '79 Ford Country Squire.

What kind of service do you have from your heater? If you make it blow full warm front and rear with windows opened if you can't stand it, do you have full warm air and does it help cool the engine?

The heat is weird. I just got it back from getting a new radiator, and the guage now sometimes moves erraticaly, and at a stop sometimes the heat turns ice cold. Im thinking maybe air in the system. Im also noticed that when i stoped to check it tonight, it sounded like bubles from the overflow.. yet it wasnt over heating. grrrrrrrrrrrrrrrrr

The heat is weird..., and the guage now sometimes moves erraticaly, and at a stop sometimes the heat turns ice cold.. maybe air in the system..when i stoped to check it , it sounded like bubles from the overflow..grrrrrrrrrrrrrrrrr

Yeah..filling it can leave air in hte system but this clears rapidly if all else is normal. TO enhance air purge, I suggest this trick: block the one way valve of the radiator cap like this

www.avigex.ca/xport/cap.jpg

and maintain the overflow tank at normal level

This keeps the cooling system at atmospheric pressure and lets all trapped air that goes to the top escape easily to the overflow tank (instead of being kept compressed inside) and when cooling it sucks coolant from the overflow tank to fill up the void Within 2 or 3 heating/cooling cycles, there will be no air left in the circuit and return the radiator cap to normal. If it keeps doing "bubbling" and weird heating.......and if running the cooling system at atmospheric pressure (in winter temperature) causes increased boiling, there is a internal cause.

Thanks... i will give it a try!

ok.. Im right back at square 1.... new radiator, spraying out the cap.. bubbling through the overflow.... and almost no fluid in the radiator.. yet everyone says its not a head gasket.

Can you see bubbles popping out of the radiator when running engine with cap opened and liquid filled to the top?

I will check when its done snowing! But im courious.. if its a head gasket, how come the exaust is fine and the oil has no water in it?

Well I would surely not want a blown gasket, but water is a normal byproduct of combustion anyway and is carried through the exhaust without no one noticing it..except when exhaust pipe is stil cold and some drops condense and drip down from the rear...so a few extra drops carried as a little more steam is unnoticeable. Oil contamination? Yeah, I'd expect that too, but I have carried blown gaskets for long period of times without noticing obvious signs in the oil....so I'm not sure how much leak is needed for that to show. ANd I can tell you I'd wait and wait before deciding to go for lifting the head....but after I'm really tired of blowing steam off and I finally play the big game with the air hose connected to the spark plug holes , then if it definitely shows...there are no questions left....if the air I force into the cylinders ends up bubbling out of the radiator, I'm convinced.

Well fortunatly for me its still under warranty. i just bought it 3 weeks ago. I have no paid a cent for repairs and the dealership (small used car shop) so far has been great. Its a 95 with 3.1 with just 48k on it.

Well fortunatly for me its still under warranty. i just bought it 3 weeks ago. I have no paid a cent for repairs and the dealership (small used car shop) so far has been great. Its a 95 with 3.1 with just 48k on it.
That is a great car, worth keeping, even though it was said GM did it hastily. Front end a little fragile, but easy to maintain. I've got mine for 11 years now, have only about 80kmiles on it, and enjoy riding it. Composite body shows no age, and gaz mileage with the 3800 is great: most economical car since my '61 Studebaker.

ok.. Dropped it off again today.. Checked the bubble theory... no Bubbles can be seen coming from the radiator...

ok.. Got it back today, Now they say the water pump was shot... we shall see!

I have had the same problem on a 1998 Trans Sport as follows. The engine started overheating but when checked the rad it was full of dex-cool. I had to stop vehicle as it heated up to the point where cylinders automatically shut down which is a built in safety response. Another sign was there was no heat. I could not drive the van a kilometer without getting the temp guage to red line. The rad was full of coolant, but coolant would overheat and shoot out of verflow, there was no heat inside the van and the van temp guage would red line if I continued driving.

I finally got it to a dealer and they told me I had an air pocket in the coolant system as a result of a blown head gasket. They found coolant spraying out of spark plug when removing plugs. I think you have a blown head gasket as this is common on these vans.

I had a car not to long ago which had the same symptoms, the Head Gaskets were fine, it turned out to be the connector that goes into the intake manifold (LOCATED under the throttle body) which connects to a pipe going to the heater core, this connector was blocked, I since have replaced many of these when I have a customer complain of excessive pressure, erratic heating, or overheating.

These systems are very sensitive to air, and when bleeding,it must be done through the Bleed Valves on the cooling line.

Good Luck

Mr.Rob

Lic Mech Auto/Truck/Trailer...Ect..

I picked it up yesterday. No more spraying from the radiator cap, But sometime theres no heat what so ever especialy at a long red light. it come out ice cold. The thing that worries me is that when i shut it off, it sound like bubbles coming from the overflow.. yet its not overheating.

OK after changing the pump, it is legitimate that some air could have been trapped, so remove the plug on top of thermostat housing to let any residual trapped air escape.
www.avigex.ca/xport/thermostat31.jpg
Keep radiator fully filled and maintain overflow tank half filled.
Any trapped air is eventually entrained with coolant and ends up at the top of radiator and is purged to overflow tank and coolant is siphoned back in the engine when it cools down.

If the condition does not clear within a few engine cycles, some other weird cause will have to be found.

Looking for anything, make sure hoses are OK (no peeled off skin from the inside that could block the flow) Check for visible coolant flow looking from the opened radiator cap (open before engine is warmed up) and feel the hoses for uniform temperature distribution.

mrrob, i have a 3.1 does it have the same part?

Yes, All 3.1 v6 engines have this connector, if you removed the Throttle body hose and look directly under it, you will see a Silver connector (coolant) with a black pipe connected to it, you will have to removed a bolt that holds the pipe in place.

I have replaced over 40 of these, and every complaint was either no heat or pressure in the cooland bottle.

If you have ABS you will have to unbolt the master,( unbolt at vacuum booster) do not remove any brake lines, you will have enough room to work once it's out of the way.

The connector uses a 15/16 wrench, be careful when removing , I have had a few break, (make sure you inform your customer in advance so there is no surprises, (if you end up having to removed the intake manifold.

This connector is only about $25-$30 bucks, you will want to inspect the heater hose and metal pipes which connect to the heater core, this is the time to change them.

Good luck.

Mr.Rob

EH.....photos of that operation are requested !!! If you change the part, photos of the old one and of the new one; experiences like that need to be documented and kept for others....
by the way, Rob, can you identify the part on any of those 2 drawings?

www.avigex.ca/xport/heaterinletpipe.jpg
www.avigex.ca/xport/heaterinletpipe2.jpg

According to your description, I would think of part 1 in figure 17 ??????? but then, I would not see the connection with the problem...so, I need some light..

BTW, mmrob, being harassed by a very cold January, I'm just ecstatic now to know Hawai is in Canada lol ! I just felt much better ! ..mmm if it could be...AHHH...

well as of right now, its just sitting in the driveway. The radiator seems to be filling with air. The guage was bouncing all over the place. I checked the radiator and the top of it was ice cold. I slightly opened it and for the first 10 seconds all that came out was air.. then the hot coolant.

How much coolant do you need for make up? Just for a test, did you try to run it WITHOUT a thermostat? This would not solve any problem by itself, but this is a free test at least....Gaz (air, CO2..) is poor heat conductor and thermostat looses more heat through conduction that heat received from gas, so I think in the conditions that prevail at this time, it stays closed. Of course, I'd like to find some cheap cause, like an inverted thermostat (I've seen this before, while in fact it did not have any large consequences)...Frankly, and sadly, (and I'd like to be wrong), but I've never seen situations like that, these signs speak for themselves, to be anything else (short of a cracked block) but a blown head gasket...and 3.1's have written history of that, and if I evaluate your wording correctly, it seems to get worse and worse... I just say this so no chance is lost to exert your buyer warrantee if need be.

The coolant level is down by about 3" when looking into the radiator. Theres no water in the oil and the exaust is good.

just got it back again... and still when i shut it off... theres Bubles coming out of the overflow.

As brought forward by GTackett, a blown intake manifold gasket is to be investigated too: I think it is less common with the 3.1 (while well known with hte 3.8 and, seemingly, with the 3.4). Since manifold is maintained in a vacuum state most of the time when engine is running, coolant can be ingested and exhausted and at the same time air is being sucked in through radiator cap to replace the coolant. THis will show no bubbles popping from radiator.

Its going to my local pontiac dealer friday.. but when i spoke to them, they laughed and said its a head gasket... we shall see

Yes it is Part # 1 on the first diagram, the relationship to this problem is the connector gets Blocked, thus causing a flow problem, also causing a heating problem, I saw a customer just yesterday who's car I fixed in November and he was Very Happy, I am not saying this is the problem you have but it's worth the time to investigate and make sure this connector isn't blocked, (the part is only about $20).

Also again make sure none of the heating pipes, (on front of engine and the one that goes under the intake have any leaks, these cars hate "AIR", and air pockets cause these systems to overheat.

Anyways I hope this helped keep me informed.

Mr.Rob

Lic Mech Auto/Truck/Trailer
24Hr Mobile Service Pickering Ont.!

well.... according to pontiac.. its either a head gasket, or a cracked head.

Sorry to hear the bad news, yes unfortunatly this is the worst senario, but make sure you get a few quotes, ask your friends who they have taken their cars to, give them a call and get a second quote, it never hurts.

Good Luck.

Mr.Rob

The good news is that its supposed to be under warranty. I just bought it jan 4th from a used car dealer here on Long island NY. The law is on my side, so im drafting a letter today requesting a full refund or finaly repairing it. Since it has just 48k, by NY law he must refund my Money. Now the task of getting him to comply! Thanks to everyone that tried to help! Tim L

Well the good news is, After threatening the NY sate lemon law, the dealer agreed to fix or replace the van. Not sure i did the right thing, but i agreed to let him fix the heads.

If they have the ability to do it and you like the car , this is a desirable solution. Hope they do not consider "doing it" is enough: the result must be demonstrated. Blown gasket is the usual scheme...weird things like cracked block or head would have required extreme conditions, which are improbable....but he previous owner had probably gone through all your questioning before opting to let the car go..."he" was no longer under a warranty...

EDIT Fev 28: well I'm looking forward for you to have all of that settled down to your best satisfaction..too bad it turned out so dissappointing.

yup, im hoping the fact that it was a 1 owner vehicle with just 48k on it that it wont be a total lemon.

well its been 3 weeks since i dropped it off... and he has not even started the repairs! Tomorrow im demanding my money back.

well got the thing back last night. The dealer actualy dropped it off at my house while i was at work to avoid me! I started it today, and the engine is surging, and the tach is slightly bouncing up and down. Drove it for 20 mins and the service engine light came on. Now its idling at 1500 and at lights if feels like it wants to take off. dear god now whats wrong with this thing! arghhhhhhhhhhhhhhhhhh

FIrst thing: at least, will it keep its coolant in now?

Idle speed is controled by the idle air control motor, and this one is controlled directly by the computer based on inputs from all sensors...so given the extent of the job done on the car, having one connector awry is a possibility. Faulty EGR valve may be also involved...just disconnect the vacuum hose that acts on it for a test.
I just wish you end up with a working horse....after all, with all the parts they have replaced before addressing the culprit, it could finally be able to keep up for a while....

I just checked the codes. Its giving me codes 21 and 22.. any ideas? thanks!

YUP THis is Throttle Position Sensor. It is relevant with symptoms you describe.
checl www.avigex.ca/xport/dtc21.jpg
www.avigex.ca/xport/dtc22.jpg
(scans from the 3800 pages but similar for 3.1)
I have been able to lubricate mine once by removing it and forcing WD40 through any opening I could find..I think I used the shaft bushing gap...
THis is a variable resistor and after a while it gets dirty and makes poor contact with the "wiper" that collects the voltage and feeds it to computer. WHen it looses and makes voltage again, it considers that as rapid throttle position changes thus variation in fuel delivery.

Thanks for the help! I just ran it for 45 mins, and it didnt overheat and the temp gauge stayed within the normal range. No bubbling hissing or anything! I priced the tps at Autozone and they want about 29 bucks. I think i know what it looks like.. so i might do what you said with the wd-40 Thanks again!

..I think you should try to measure the voltage at pin C
www.avigex.ca/xport/tps3.jpg with key ON, you should measure voltage on the "wiper" while somone slowly presses throttle down to floor. YOu should measure a continuously rising voltage from about 0.5 to 4.5 volts. If you have only near 0 and then 5v all of a sudden, this means the resistance track is cut in 2 pieces and then you need a new sensor.

Just had a Oldsmobile 3.1 that did VERY simular things... start it up, ran very great until it got hot, ( and thats the key thing, it HAS to be HOT)then big burps of bubbles in the overflow tank!
turned out to be a snapped cylinder head bolt between 2 of the front cylinders...
As you mentioned, no antifreeze in the oil, but when the car was parked facing up hill, it seemed as though there was a fair amount of water coming out the exhaust. If you really want to prove it, put in flouresent dye into the antifreeze, then for sure you will see where its going. The cold air you feel in the heater is because once the cylider leaks exhaust gas into the cooling system, the bubbles will give you cold air out the heater.
Sorry. I think that despite what the service station says, its broke in a bad way. if the oil isnt contaminated, it may be worth saving

Well it seems to be running on coolant wise... I have not tackled the tps problem yet due to the snow, and the fact that since i needed to get back and forth to work i had to put my Geo metro on the road. I have run it for about an hour in my driveway and no bubbles.. no over heating so far.... maybe its fixed?

ok. Now it seems theres liquid..coolant? dripping down the block near where the block and Tranny meet. Its hard to see where cause the exaust manifold blocks it.

You have had new gaskets installed all around...heads and manifold..so if if leaks significantly and looks as it is coolant, I would consider removing the valve covers and checking the head bolts are properly torqued...there is always an unwanted and unexpected possibility that the gaskets have settled a little and the bolts could reveal as undertorqued now. Alas, this is not very interesting after all of what you have been through.......

IS IT POSSIBLE THAT ITS FROM THE tHERMOSTAT HOUSING OR MAYBE THE TUBE THAT RUNS AROUND THE FRONT OF THE ENGINE?

A definite possibility. These items have been displaced and stressed and that can have had that result on piping and other gaskets.

The mechanic said its oil. Most like;y from the rear main seal. Im thinking it might be the oring for the distributor cause i see some oil by that also.

The mechanic said its oil. Most like;y from the rear main seal. Im thinking it might be the oring for the distributor cause i see some oil by that also.The oil shaft o-ring is notorious for leaking on the 3.1 and 3.4 engines. If you look under the throttle body, you will see a silver cap about 1.5" in diameter. This is the top of the shaft. On older engines with a distributor, this is where the distributor would be. The o-ring on our engines wasn't designed for hi temp/pressure conditions and it deteriorates. It seeps oil because one of the main oil lines flows right through there, so it's under higher pressure then where other places might be. It should always be replaced when the manifold is removed as it's easy and takes about 5 minutes. An oil leak here would drip down the tranny and appear to me a main seal leak. Any reputiable mechanic that has worked on several of these engines should know that...a GM dealer definitely would know it.

You may be able to get to it by just removing the throttle body. If not, then at least the upper manifold/plenum gets removed. Remove the bolt holding the clamp down. Then use a pair of channel lock pliers to pop it straight out. On mine, it stuck so I had to use a small pry bar on the channel locks (not underneith) to pop it up. My o-ring was completely dry and brittle, cracking easily. Reassemly is reverse of removal. You can also put in a paper gasket under the cap to help prevent future leaks in case the o-ring fails again. Just use a gasket from an earlier engine that did have the distributor. Sorry I don't know the part number.

Are you saying I dont have a distributor? Then whats holding the cap up? :)

.....as suggested in CDRU post, yours is one of these "older engines with a distributor".... lol