Mechanics

IDING OVERHEATING PROBLEM

2002 Pontiac Montana

Engine Cooling problem
2002 Pontiac Montana 6 cyl Front Wheel Drive Automatic 77000 miles

PROBLEM - OVERHEATING:

1. Wondering if I have a " fan relay problem", or " fan problem" (like with just one fan?) Vs. Gasket problem?

2. What does it mean if a fan feeds back through the system? I saw this on a NAPA parts site for " electric cooling fan relay". Could this be the " problem"?

3. Could it have to do with the metal thing that attached to the water pump?

4. Could one fan be kicking in - while the other isn't kicking in -- and if so, is this a relay problem?

5. I looked up fans for Pontiac Montana. It says there are two types - one for driver's side and one for passenger's side. I only thought the fan was on the passenger side - so confused.

SYMPTOMS:
* Van with engine running, most of the time the heat won't kick in for about 30-45 minutes, then it'll be like the fans " cough" and then all of a sudden there is a nice blast of hot air, and the heat stays on.
When heat kicks in, van doesn't overheat.(Needle down to normal level).

* Van can be forced to " overheat by revving engine - Pontiac Dealership Service Dept. Did it.

* If parked and idling, it doesn't overheat. Drive and sit at a light with a warm engine, it will overheat.

* It doesn't like moderate to steep hills - up or down. Up - is worst. Will overheat.

* If system is bled, can be fine for a day or so, then problem reoccurs.

TESTS from my research:

Oil is clear, just starting to look like it will need to be changed (it's due in 500 miles.)

Coolant " doesn't splash out" of rad (coolant at neck level before engine start), on start up.

Coolant still is at full level in overflow tank.

A: I'm not sure if a hydro carbon test was done.

B. I don't know if these garages did a pressure test. Back in October when first picked up van out of second storage, Shell Station (here) did a pressure test and it tested " fine".

HISTORY:

I love my van; acquired from dealer in November 07. It did a 12,000+ mile road trip then developed overheating problem intermittantly, which has gotten increasingly worse. The problem FIRST surfaced AFTER being stored for three months outside - we had a lot of rain and cold in Dec - March 07-98.

The first signs of a problem after starting to drive the van again was the sytem light would also be on for about 3-4 minutes on start up, then off for remainder of any outting, until the engine was shut off and then on restart, the light again would do the same thing, etc. It was not a serious problem then. And the issue at the time was whether to store it - again- or sell it. Opted to store it / table the decision. So, it was stored from July - October 6, 08.

Picked up van. Engine light repeating the same as above. Van started having an overheating issue - which had only happened once in about May 08. Picked up van in WA and drove up fine to my city, then within two days the overheating problem surfaced. When I picked up the van, the coolant level was normal, then when I checked it the night it overheated, the overflow tank was dry. BUT then I filled it with Dex-Cool, and since then it hasn't changed levels (i.E. No leak).

After filling with Dex-Cool, went back down to WA (bigger cirty)*, no problems, drove a lot, no issues. Maybe drove gee, 160-200 miles? Drove back up - overheating issue resurfaced, this time on coming up a moderate hill near home. This time overflow tank is full. Starting to notice heat is SLOW to 'kick in'. Strong fan - but blowing cold air.

[* I can tell you privately where I am - I just don't want it published on the Net.]

Someone told me try putting on " defrost" " 5" (highest blower setting), and highest heat setting. Did 'that'. Seemed to work initially, to keep it from overheating when it started to have the needle rise.

Garage #1:
Too into my very (!) Trusted mechanics garage, and it would never act up at the shop, so problem couldn't be isolated. Mechanic (John / Owner) would bleed out the line, thinking maybe air had gotten in somehow? Van would be " fine" for 1-2 days, then problem would repeat - while it would idle " fine" for over an hour at a garage when shop mechanic would test, for me when I'd pick up the van, drive about 5 miles, problem would resurface - idle at a light and it would start to overheat, or on an uphill. Second time in shop he put a new thermostat in it, and did tune up, checked hoses, wires, etc. Said waterpump looks okay. Belts are " fine".

Pontiac Dealership Service Dept:
Took to Pontiac dealership and the guy there put a scope on it. Says 3rd cylinder is misfiring, reading a problem with oil pump gauge (not diagnosed) and the fans couldn't be controlled with the scope - and said they should be able to do this. I notice some white smoke out of back at the time - on a cold morning, with engine cold. Pontiac said it was " nothing" and normal for cold engine and colder weather. Pontiac concluded " no diagnosis" - except - check fans, and oil pump (or pressure?) Gauge - and find out why 3rd cyl. Is misfiring -- then if not this, then gasket problem.

Pontiac was able to " force it to overheat" by revving engine.

I drove it home - about two miles - and it kept trying to overheat, especially idling at the traffic lights.

After it had been into #1 garage twice, (had been towed there twice), I took to #3 diagnostic at another trusted mechanic. It was towed there after overheating about one mile from home.

(Should mention, I volunteer for a nonprofit organisation - so Mechanic Shop #1 donates all their labour. #3 is helpful and trusted but no longer donating time. So need to be very conservative about how I spend our funds).

Garage #3:
#3 shop owner " Alex" after having one of his shop guys putting an hour into it, started thinking it is likely the head gasket. Said intake valves were done. Said water pump looked okay.

SHOP RATES/ LABOUR TIME QUOTED:
Rates: I am being quoted $79/ hour shop rate and 18 hours for labour, + parts. Estimate is about $2500 to do the job. How much should I be expecting in labour hours and if it is a blown gasket, what are normal rates for machining / grinding of flat heads?


QUESTION: Can a van in this condition be " traded in"? Our nonprofit isn't in a strong cash flow position to deal with trading in - so would like to fix, if possible, and it makes sense to do so.

Thank you for your help! Appreciate your answer.
Making donation - based on what our nonprofit can afford presently.
Avatar
Tigerseye1
November 17, 2008.



Hello –

If I understand you correctly you would like an opinion if the van should be repaired or traded in the current condition?

If this is the question only you know the answer and what you can put into it. I show about 16 to 18 hours to perform a complete head job and the cost is pretty close.

The main thing here is will that also fix your overheat problem? Probably not. With the trusty van sitting (even driving for that matter) from some of the things I have read, Dex-cool has a tendency to kind of, gum up…..This obviously will plug your radiator, heater core (which may be why your heater quit), thermostat etc. You must keep this flushed and clean on a regular basis. So unless you plan on doing a really good flush of the cooling system it will still maybe overheat.

As for me, and I tend to go on the fix it now so I don’t even think about a problem later way, I would replace the radiator, heater core, thermostat and do a flush of the block with the engine running that it would never forget. Then I would go back with Prestone, the green.

Next, you brought up the cooling fans. It looks like it has dual fans on it. You can check them by starting the car, turning the AC on and if they don’t spin you have a problem. So you would need to make sure those are working or you are back to that overheat thing.

According to Kelley Blue Book, trade in on the vehicle in excellent condition is about $3515. Fair which means it is still running is about $2665. You can look that up.
http://www.kbb.com/KBB/UsedCars/PricingReport.aspx?YearId=2002&Mileage=77000&VehicleClass=UsedCar&ManufacturerId=40&ModelId=274&PriceType=Trade-In&VehicleId=4678&SelectionHistory=4678%7c29450%7c67037%7c0%7c0%7c&Condition=Fair&QuizConditions=

So you need to see if the repair is worth it to you. To get the heads and get the cooling in order you may be up to about $600 in parts and about 6-$800 in labor. You really have to be motivated to replace a heater core. Maybe, just maybe when they flushed the core, they just put full pressure right through the core and had outstanding flow and you wouldn’t have to replace it.

So tuff question: Again, if you don’t fix the cooling problem, you will just blow the head gaskets again.

Everyone will have their own opinion on what to do here. If I was doing the work myself and needed the van….I would fix it. If I had to pay someone……well, as long as the rest is in outstanding shape and will last you a good while it may be worth it. Only 77K is not that many miles. But sitting is hard on things…..seals get hard, rubber starts to rot…….

I am sure this isn’t exactly what you wanted. If not and you would like another moderator opinion let us know and we will do that.

Hope this helps

Please let us know if what the final fix was for your car so we can better assist others. Thanks!

Thanks for the donation

Find a car repair manual for your car repair questions.

ImpalaSS
Nov 17, 2008.
Thank you for your reply.

Per your comment: " This obviously will plug your radiator, heater core (which may be why your heater quit), thermostat etc. You must keep this flushed and clean on a regular basis. So unless you plan on doing a really good flush of the cooling system it will still maybe overheat.&Quot; Q1: The van heater didn't " quit". It just is slow to kick in -- if the heater had blown, it wouldn't kick in at all, ever, right? And sometimes it kicks in right away still, other times takes 30-45 minutes, then kicks in.

Q2: Per your comment: " and do a flush of the block with the engine running that it would never forget. &Quot; Flushing and cleaning block and rad: Is this something I can do- or - does it have to go into a shop to do it?

Per your comment: " I would replace the radiator, heater core, thermostat. Then I would go back with Prestone, the green.&Quot; Q3: Can I use Prestone when Pontiac manual only says use Dex-Cool?

Q4: Cost on parts for heater core (is this assuming the heater 'doesn't work at all' - as heater does work it seems.)?

Q5: What type of rad do you recommend - after market or certified? Or is there not much difference?

Per your comment: " Next, you brought up the cooling fans. It looks like it has dual fans on it. You can check them by starting the car, turning the AC on and if they don’t spin you have a problem. &Quot; Q6: Fan on passenger side spins - at least when hood has been raised. Is there also a fan on the driver's side? When I did a search for fan assemblies, I saw driver's side fan listed - two types - (also two types for passenger side). How do I know what I need?

Per your comment: " just maybe when they flushed the core, they just put full pressure right through the core and had outstanding flow and you wouldn’t have to replace it.&Quot; Q7: Something a rad shop would do, dealership, or regular high end mechanic shop? Labour time units?
Approx. Cost?

Summary: Sounds like we " replace the radiator, heater core, thermostat and do a flush of the block with the engine running that it would never forget. .(Nervous about this. Then go back with Prestone, the green. Hope this is okay when Pontiac warns to only use Dex-Cool.)

Q8: Can we use the same new thermostat that was just put in -- less than a week ago -- or does it need another new one? (Would think this new one is fine - but asking.)

You also seemed to think " heater core" might be able to be saved?

Q9: Yes, please. Considering this is a high end repair, it seems, our nonprofit would humbly appreciate another moderator's opinion /insight as well. Thanks.

Per your comment: " Please let us know if what the final fix was for your car so we can better assist others. &Quot; Q10: How do I do this? Of course will provide feedback. If we can help others. This is 'what we do'. Best way to do this -- do you mean 'post in free postings for forum'?

Per your comment: " I am sure this isn’t exactly what you wanted. If not and you would like another moderator opinion let us know and we will do that.&Quot; Yes - please - a second opinion from another Moderator would be greatly appreciated since we are talking about a costly repair.

Thank you.

.

Tiny
Tigerseye1
Nov 18, 2008.
I agree with ImpalaSS, 77k is fairly low mileage considering what you could buy with the amount of money they want to repair your van.
1- slow heaters usually are indicators of partially plugged heater cores, a victim of Dex-Cool. As far as a backflush, a radiator shop is your best bet, they use amachine that will flush it without damaging theheater core, cost is around $100.
Radiator, I would go with a Modine or other national brand, simply for the warranty, and quality of construction, remember when buying parts, cheaper is exactly that
Dex-Cool, there were huge problems with it, replacing it with a universal green is your best bet.
Fans, you say only one fan runs. Is this with the a/c on? Or when the engine comes up to temp?Turn on a/c and see which one turns on, then turn a/c off and let it warm up to see what turns on.
You could reuse thesame t-stat since it is so new, I do suggest a new seal fo rit, that one is in a bad spot and a leak wouldnt be good.
All in all, the previous advice is right on the money as far as the course I would take.

Tiny
Jack42
Nov 18, 2008.