New Stant thermostat - bad, or stubborn air pocket??
-Cut heater hose and installed prestone "T".
-REMOVED old thermostat, reinstalled neck.
-Ran the hose and engine and heater for 20 minutes,
coolant totally clear.
-Installed new thermostat, 195 stant brand,
made sure the thing was aligned the right way
(teeny hole going upwards), and filled with G05
(spent a lot of time reading about coolants before this)
-Then i followed the correct procedure for getting out all the air,
96_awd has posted info in the past...
Now, my temp gauge hovers on the low side, and for no reason,
it will ocassionally swing up to 'normal', and then go back down-
this event is done in like 30 seconds.
I have a 90', and with a actron superscanner, you CAN read live data, and yes, the temp sensor also shows a rapid movement of temp---hangs mostly
at 175-180, then shoots up to 195-205, then back down.
I do not think it retrieves it's data from the gauge sensor, the van has 2 coolant sensors....so it would seem from all this that the gauge reads good..
-The van has a rear heater, installed 'aftermarket'.
Anyone deal with that before? I wonder if it has trapped air.
-I noticed, when repeated trying to purge air with cap off, that as van is getting hot, there IS a 'belching' effect of coolant level, it does not slowly
rise up...although right now it is so full (and yes, recovery tank has coolant
in it) that it simply overflows, what a mess--the 'belching' action is not readily visable anymore, like it was when coolant was an inch below the cap.
- I think i got a bad tstat!
Any thoughts, anyone?
marty
My money would be on an air pocket. The gauges are measuring o.k. In the glove box manual it says to warm up the engine (no driving) in the garage with the rad cap to the first notch. This allows air to vent to the expansion bottle. Try that & keep the pipe in the expansion bottle under water, so it will top up the rad when coolant contracts.
This is to get out the air only, do not drive the car like this!!!!!!!
It might help to put the front axles up on jack stands to help the air reach the upper rad hose.
Is your water pump good? a weak pump can allow low flow of coolant and exacerbate(sp) this problem.
Aeroman.
Last edited by Aeroman59 : 12-23-2007 at 12:30 PM.
Water pump, hmm.. no squeals, so i think it's OK.
Van only has 25K, i think it's fine.
I was feeling the upper hose while running (hot),
it certainly gets firm, lots of flow must be present...
marty
Is your water pump good? a weak pump can allow low flow of coolant and exacerbate(sp) this problem.
Aeroman.
What makes a water pump "weak"? Unless a fin is broken or the belt is slipping, what is it about the mechanics that makes it produce less volume or pressure?
You might need to look at that pump anyway. I've seen a couple of them at 25K with all the fins corroded away and the impeller looks like a cheese slicer. Oddly enough, I have seen this only on Aerostars, but's that's about all I drive these days. Maybe some of the better mechanics here can tell us if that is peculiar to the Aerostar or a common issue.
__________________
Dave Mac
94 XLT Long 237 K, still driving while I work on the other one
92 XL Short 138 K and back in the workshop
89 Tempo 157 K and still haven't worked this one out
The coolant that i removed looked really good, like new,actually.
Also, if it was a bad pump, wouldn't the temp be consistently high?
Right now, it is running too cool...
Thanks,
marty
Water pump, hmm.. no squeals, so i think it's OK.
Van only has 25K, i think it's fine.
I was feeling the upper hose while running (hot),
it certainly gets firm, lots of flow must be present...
marty
Hose will be firm, only shows the system is pressurizing. Flow is another matter. Can you feel a bit of a surge after squeezing the upper hose?
You can test the thermostat in a pan of boiling water (2 pans is better) bring 1 pan to the boil & the other just hand hot. Thermostat should open & close when you switch between pans.
I had your problem & it was air in the system. It took a few months for the air to purge. During this time I read about the refilling procedure in the glove box manual. They devote quite some space to the topic ,so there can be a bit of a problem getting the air out.
I will post the manual to you if you like.
There is also a possibility that you have a slight head gasket leak. However this would likely get some coolant into your engine oil & you would have milk shake chocolate soup oil!
FTR my 3.0L runs at 200*c 180 is a bit low. Whats ambient temp in your area?
ATB Aeroman
Last edited by Aeroman59 : 12-24-2007 at 11:28 AM.
Reason: Update.
You might need to look at that pump anyway. I've seen a couple of them at 25K with all the fins corroded away and the impeller looks like a cheese slicer. Oddly enough, I have seen this only on Aerostars, but's that's about all I drive these days. Maybe some of the better mechanics here can tell us if that is peculiar to the Aerostar or a common issue.
This is a common problem with Contours/Mystiques, mainly because they have factory plastic impeller. The steel ones last longer.
This also proves the need to regularly change your coolant.
__________________ '96 Ford Contour 2.0 I4 MTX 77k mi- Rear Ended 12/22/07 '97 Ford Aerostar AWD 4.0L v6 AT 81kmi '97 Chevy Lumina 3.1 v6 ATX 135k mi Parents old beater, temp vehicle
You might need to look at that pump anyway. I've seen a couple of them at 25K with all the fins corroded away and the impeller looks like a cheese slicer. Oddly enough, I have seen this only on Aerostars, but's that's about all I drive these days. Maybe some of the better mechanics here can tell us if that is peculiar to the Aerostar or a common issue.
As a former Ford tech, I also saw a lot of them on the 3.8 engines that had head gasket problems. I think the corroded fins on the water pumps of these engines accelerated the need for the head gaskets, but that's just my opinion.
All the water pumps I've replaced lately have been new (not rebuilt) Airtex branded pumps and they've worked real good for me. I like the new ones because a lot of the rebuilt ones seems to have a poor mating surface.
Sometimes it takes a little while to get the air out of the rear heating system. I'm sure there are other great brands out there, it's just that for something like this, I avoid the national chain stores.
Aeroman59, never thought about flow as compared to pressure, good point.
Have not tried your test yet....
Wow, it took that long for the air to purge on your system-with my hacked-in rear seat heater (it is an extended cargo van, labeled "incomplete vehicle' on door jamb, it's a conversion van) i thought right away there is a pocket of air somewhere.
I have the manual, thanks for the offer!
I think i will do the recommended 'purge' once more--my ambient temp yesterday was
10f, it's in northern illinois- thats why I want the maximum amount of heat!
(when it swings up, i can tell the difference in the vent's heat,
Plus, running cold hurts MPG, that is another bummer!)
Thanks again, guys,
marty
Sounds like an air pocket. You could also use your newly installed "T" to bleed the system. Attach a short length of hose and put the open end down into a container with coolant, so air can pass out but the coolant prevents any air backflow. As the system warms up, there will be coolant displaced, so don't fill your container too full to start with. Keep the bleed hose/container at the highest point of the cooling system. (i.e. don't put on floor and cause a siphon effect.)
This happens nearly every time I've changed thermostats. After a few days of driving the system will eventually purge itself.
Last edited by aerocolorado : 12-25-2007 at 01:32 PM.
I have seen "sticky" thermostats before. I betcha that is the problem. While the air bleed procedure is a good one, the system will purge itself in 3 or 4 cycles.
i watched mine do that for 1200 miles recently on my 4.0l. I assumed it's just the normal functioning of the t-stat. I had just flushed & refilled the system and ran it long time till it wouldnt take any more coolant. Then drove it a day and rechecked it cold next morning before leaving on trip.
from my experience the ford temp gauge is sorta cheap and reads low in later life, but your monitor thingy should be tellin the truth. aftermarket t-stats (& other parts) sometimes are too cheap. Yep I've had a aftermarket w-pump blow the gasket after a year or two due to poor mating surface. new gasket leaked at same place.
my coolant had lots of oily stuff in it which i really dont like. the oil seems fine tho with no gaining of level or even a hint of moisture. any ideas guys? 1997 4.0l awd.
one of my next projects may be to try and replace the factory hoses with new made-up ones. tired of paying Ford hundreds for the hoses every 5 years.
about the best easy to obtain thermostats are the Stant Premium line in stainless steel, they open and close gradually with temp rather than snapping full open then close . use only the 195d F stat in Aeros, the ECU/PCM has its firmware programmed only for the 195d stat.
my 96 4L temp gauge has read in the lower 1/3 since new, PCM scanner reads rock steady 195d F closed loop on freeway cruise. see Rangers and Explorers showing bottom of temp gauge also.
oily film in coolant indicates a head gasket leak, cylinder to coolant passage, with only high pressure combustion gases and oil forced thru into coolant. common for only one way leak flow until after years the coolant eats thru the head gasket at leak.
put a UV leak detector dye in your oil and look for it in your coolant after a month or so.
run a leakdown test on cylinders, will pinpoint the cylinder leaking. do both head gaskets.
Hmmm. I wonder if the Stant brand has different grades of product,
i bought mine at discounter (murrays auto).
I wondered if a tstat should move gradually, instead of 'snapping open',
thanks 964wd for answering what i thought would be a fool's question...
Interesting about noting that most dash gauges read low,
my 88 and the 93 did that also, but i did not have a scanner to read CTS
values on those rides...
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