Shop Oldsmobile Head Gaskets

There are dozens of reasons for overheating, depending on the condition of the cooling system and yes, it does require a thermostat at all times.

thermostat was rusted solid

That's not a good thing. You flush the engine and coolant system out before replacing the radiator?

Does it overheat sitting at a light or while cruising?

Thanks for the feedback. Car didn't run for a year. It overheats while sitting.

Do the electrical cooling fans come on when it is getting hot? If you have the ac turned on, do the fans come on?

When it reaches 190-200 low coolant light clicks on as well as fans.

Did you flush out the system really well, including the heater core?

Yes I did n still overheating.

When the fans come on, is the air blowing out of the fans hot? Feel the heater hoses. Are they hot?

Heater hose is hot and building pressure. Fans are blowing cold. If there is any trapped air in the system will that cause it to overheat.

Makes us wonder why it was sitting so long.

Yes, that will definitely cause it to overheat. If there is combustion gases getting into the coolant system, no amount of bleeding is going to work. A cylinder leak down test can reveal if there is a head gasket problem, cracked head, or cracked cylinder wall. You'll see bubbles in the coolant system when you pressures the cylinder. Compression tests may not give you an indication if the leak is small.



Some of techs use vacuum coolant lift system to do refills on those, because they do like to trap air sometimes.

Here is the service procedure:

FILLING PROCEDURE

1. Close the radiator drain cock.

NOTICE: When adding coolant, it is important that you use GM Goodwrench DEX-COOL@ or HAVOLINE DEX-COOL@ coolant. If Coolant other than DEX-COOLS or HAVOLINE DEX-COOL@ is added to the system the engine coolant will require change sooner-at 50 000 km (30,000 miles) or 24 months.

NOTICE: Do not use a solution stronger than 70% antifreeze. Pure antifreeze can freeze at -22°C (-8°F).

NOTICE: This engine uses DEX-COOLS and GM coolant supplement (sealant) P/N 3634621 specifically designed for use in aluminum engines. Failure to use the engine coolant supplement (sealant) and the approved coolant antifreeze could result in major engine damage.

When refilling the cooling system, add three pellets of the engine coolant supplement sealant GM P/N 3634621 to lower the radiator hose.

2. Refill the cooling system. In order to ensure sufficient Cooling System, freezing and corrosion protection, maintain the coolant protection level at -37°C (-34°F) or lower.

3. Set the heater and A/C control in any A/C mode except MAX. Set the temperature to the highest setting.

4. Allow the engine to continue idling until the lower radiator to coolant pump hose becomes hot.

5. Cycle the engine speed up to about 3,000 RPM and back to idle 5 times. On the VIN 1 engines, slowly open the bleed valve on the rear of the thermostat housing for about 15 seconds in order to release any trapped air in the cooling system.

6. After the air has been released, fill the radiator. Install the radiator pressure cap/surge tank. The arrows on the radiator pressure cap must line up with the coolant recovery tube.

7. Allow the engine to cool to the outside temperature. Check the coolant level. If the coolant level is not at the Add (of Full Cold) mark, add coolant until the coolant reaches the mark.

The static compression pressure in the cylinders doesn't hold because the pressure will bleed off through the rings. An engine's cylinder isn't perfectly sealed. The reason the pressure stays where it is on your gauge is because it has a check valve in it. This means you could have great compression, but still could be getting gasses into the coolant system.

A leak down test actually pressurizes the cylinders with compressed air. The tester tells you the leak down rate of the cylinder. Since it is using compressed air, it keeps the cylinder pressurized and any leaks going into the coolant system will show up as bubbling in the reservoir.

Heater hose is hot and building pressure

HI Tom,

Thank you for all your input. I do not want it to overheat or try getting it that hot so I have been trying to be care with it so I do not warp a head or crack it. This car does not have a radiator cap, only on the recovery tank. Yes the fluid is fine. I had off the cap on the take to see if I would get any gas bubbles at idle, I did not notice any there but that does not mean gas in not getting in the system. I did notice after about 10 minutes I seen vapor or smoke coming out of the tank, not much and the gauge in the car was only about 150 so I was not sure what it was doing that for at that moment. I took it for a drive to get it to heat more fast and I return and had more pressure and fluid coming out of the recovery tank, maybe that cap is bad too not sure. I want to do a pressure test but do not know if I can with this system only having a screw cap on the recovery tank, I will go tomorrow and see if I can get a pressure tester for that car. I will also check on the top hose and see if the pressure builds up fast, thank you, I never had heard of that one. So tomorrow I will do more testing to see what it really is doing. Also do you or anyone know if "Alldatadiy" is a good site for diagrams, making repairs info, and codes for cars, is it worth the money, thanks again for all your help. Thanks Brian

The guys here have assorted info so ask away with a new thread for different concerns. The All Data stuff is available thru them for a price - programs for all cars are expensive and I don't have direct access to them.

Libraries frequently do!

Pressure tester can be rented (free I think) from AutoZone or similar chain type parts stores.

It makes it tough when cars put the pressure cap on the recovery tank and more cars are doing that instead of on the radiator. It's fine but complicates how to know the rad is actually full itself or for burping out air when you do anything with the cooling system.

I'm concerned that you've noticed vapors at the recovery tank which is part of the pressure controlled system in this car. It shouldn't even be warm coolant over there in 10 minutes yet??

You do understand the concept of the recovery tanks - right? You know - they take air and whatever from the engine and radiator thru a small hose to the bottom of that tank which is supposed to only return liquid back when system cools, contracts and sucks it back - the idea is air out, liquid back all the time which means the rad and engine are supposed to always be free of air or any vapor. Air and or vapors will expand quickly and blow coolant in the way out to and up over the recovery tanks when things get messed up.

As you know air doesn't exchange heat worth a diddle so the engine overheats.

If it is a head gasket problem so be it. Best to minimize further damage and surely best to diagnose it right as it's a lot of $$ and effort to be wrong with that one!

Keep observing and see what a pressure test can find for you,

T

It's good news but inconclusive with the pressure test. Hoses will expand a bit and drop a pound so that doesn't mean a leak. Unfortunately you should only pressure it to the cap's rating and the pressures on combustion can be in the hundreds and need that much pressure to leak or only does it at a certain temp and some only leak one direction to cause as much hair loss as possible as you are finding out!

If you still have the pressure tester, put in on and start the engine. Watch it from cold go up - it will but not so fast as you noted by hand. NOW WATCH IT UP TO THE RATED PRESSURE AND DON'T LET IT EXCEED THAT. Realease pressure from the device carefully and let it go again if it continues to rise when alread warmed up then that does point to the head gasket. You must be careful as releasing pressure can cause coolant to flash boil and you don't want to get burned by that. Use judgment and if it continues to build up I'd call it a diagnosis for a bad head gasket.

For water pump: Without look at it's fins and seeing that they either don't spin for some reason or are corroded down to an inadequate amount it might behave at low speeds or only high speeds or something. That problem is rare and not the first place to suspect but you shouldn't just assume it works properly. If coolant can flow to radiator and return thru it cooler at lower hose it must be doing something. Also, heater would not work well if water pump wasn't pumping but that could be air in system also.

Then there's the sniffer or detection stuff for exhaust/combustion gasses in the coolant and reservior things that may help close in on the diag. Can you friend help you pin this down for you to speed up the process of blaming a head gasket or not? I hate to see you be without a car over this any longer than needed but also don't want to rush out on the headgasket diag without being pretty dang sure.

For now try again with the pressure tester but as I said don't let it exceed that 15lbs. It will normally it allowed and then some other weak link will have a problem - enough hair loss already - right?

Another thing is to look at the spark plugs. One or more might be very different than the others and then pressure tests thru plug hole or compression testing can help.

Lot's of this stuff is second nature for those of us who have worked on stuff for all these years and it's hard to pin quickly and I'm half brain dead sometimes and might be missing some suggestion! This is hands on forum work, not just point, click, copy and paste some universal textbook something.

See what else you can find or notice and let's see what we can nail down,

T

For the moment seeing smoke/steam at reservoir is not conclusive with it running hot for reasons to be found still.

It must be known full of coolant first and foremost. Not just the reservoir but the radiator. Generally if heater works there's an adequate level of coolant for some info. If not dig in and determine whether there's air in the system. Head gaskets can add air as well as small leaks can leave a reservoir full or too full and suck air in thru the leak. Head gaskets can add combustion pressured vapor (essentially air) into cooling system and cause this. That can usually be detected by feeling upper rad hose from a cold start noting no pressure when cold and if pressure is felt quickly - like within a minute or two that's too fast and more testing needed.

I don't think this model has a radiator cap on the radiator which makes it difficult to know it's full. When no pressure is in system it may bubble at reservoir when squeezing upper hose for instance and should only move coolant - no air bubbles seen.

Seems like everything else works so it could also be a clogged radiator that just can't transfer heat well anymore. Flushing whole system can be very telling and good for it.

Again - run heater on full temp request and that's a good indicator of engine temp up to boiling where heat will quit (just trust me) - if no heat is available it's usually air with the symptoms you've posted,

T

ok thank you both. i dont know much about cars thats why i figured id check around. i am gonna take it to a shop monday to see whats going on. i had it at a shop and they were supposed to flush it or w/e to get all air out but idk. and i did flush the system out tho when i put in a new thermostat because i put in some gook (idk how to spell the word) and i had to make sure all coolant was out before doing so. but i noticed you said something about the heat. i've noticed it will be hot for a minute then cold the next. the car has a .... idk info screen if you will.. that tells you low coolant low oil ect.. and it keeps sayin coolant even tho i put it in. i was told i gotta put in a code to get it to stop sayin low so that i can actually tell when its low but idk how to obtain this code. i do not have owner manual so i probably going to have to search the net. but everytime i turn the air onto defrost the a/c light comes on and i only can turn it off if i switch it to feet where the heat comes from.. and i have the temp set at 90 and it still goes from hot to cold. so are you saying there is still air?? and as for the nose bleed lol yeah my buddy said take the cap off let it run see if the air will come out like a burp lol. but i am gonna investigate this more. would anyone happen to know a price on how much it would cost if it were head gaskets? i have a friend who has a shop but b4 asking because we're not "that close" i wanna make sure i know an area of the price. thank you for you time i really do appreciate it alot

darren

ok guys i found out my problem.. my fan isnt working.. i replaced the fuse to start with and that worked.. BUT.. doing so a wire started smoking and stopped the fan.. so i replaced the wire and it worked.. BUT.. then another wire smoked.. when it was on the fan was running super speed.. the car was not even hot and the fan was flying.. i wanna assume the wires were not big enough gauge to hold the power it generated thats why they got to hot.. i also am not a mechanic but i am gonna assume that it was a rig job on whomever had the car and tried to fix the fan. but i think that it needs a switch or sensor to make the fan go slower and turn off.. because i noticed it wouldnt shut off.. so with all this being said do either of you have any suggestions?? tomor i am going to a shop but would like to hear from you guys before if possible.. thank you for your time


darren

If wiring has been altered you are going to have to see what doesn't look original. Fan working when not even called for could be that you have defroster, defog or something on - turn the climate controls off for testing or leave on heat only or vent only. Fans can be triggered with a defrost request.

Melted wire insulation! Ack! The motor may be drawing too much current or the gauge of wire really is under size. If splicing in new wire certainly try to get right gauge and color if at all possible. There could also be a relay that's burned, stuck causing fan to stay on.

With hacked wiring it opens the book for lots of possibilities. Keep things fused with proper amp fuses if any blow while working with this,

T

will do i'm gonna have some stuff checked out today thanks for the help again tom much appreciation

Darren; You replaced the thermostat because of the overheating problem? On some vehicles, it is very easy, and a very common mistake to install them backwards. Assuming that is not the problem, are you certain that you've bled all of the air out of the cooling system. Again, this can be a real pain. I've had to raise the front of a car up so high that it got a nose bleed. Seriously, though, it really can be a pain getting all of the air out. Head gaskets; It is a fairly easy test. You can take it to a shop that has a gas analyzer and have them 'sniff' the coolant reservoir for hydrocarbons. Or, most of the parts stores sell a chemical that will do the same. Changes from a blue color to yellow if exhaust gases are present.