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RPMs Go Up, Temperature Goes... Down?

Temperature Cold RPM Gauge Down

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#1 Marmaduke

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Posted 09 December 2013 - 01:09 AM

Hello all!

 

Just bought my first Subaru. It's a 1998 Legacy GT Sedan (5speed) with 170,000 miles. I'm having a really weird issue with it...

 

The temperature seems to be inversely related to my RPMs. When they go up, my temperature goes down. After buying the car, I drove it around 120 miles home, and found that at highway speeds 70-80 MPH, at 3400 RPM, the temperature gauge was a little less than a quarter of the way up. When I "punched it" to get around traffic, I could watch my temperature gauge fall to the C almost as fast as the tach went up. Once I got back on country roads, cruising in 4th gear at 35-40 MPH, the temperature gauge sat nicely at halfway.

 

Outside temperature was was 9º F. Adjusting the heater didn't really seem to help (obviously wasn't blowing hot air when temperature gauge was down).

 

I am really puzzled by this. Although mechanically inclined, I am by no means a "gear head". I'm thinking it's either an issue of too much coolant, something with the radiator, or a thermostat issue. Any suggestions on where to start? I know it's a little cold outside, but not cold enough for the car not to run where it should. Also, should I be worried about damaging the engine by it running cold? It was only at the bottom (cold) for maybe 5-8 minutes before at least returning to a quarter temperature.


Thank you for any help!



#2 travmo86

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Posted 09 December 2013 - 01:34 AM

Sounds like the thermostate is stuck open or opening way too soon. Try replacing that first. Its not a good idea to run the car for long periods cold at highway speeds. It will run very inefficient. You will probably start throwing engine light codes as well



#3 travmo86

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Posted 09 December 2013 - 01:37 AM

*thermostat not thermostate



#4 Fairtax4me

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Posted 09 December 2013 - 01:49 AM

Someone gutted the thermostat or removed it entirely, probably trying to cure an overheating issue, which on that 2.5 means head gaskets. While the engine is warm and running look for bubbles coming up in the overflow reservoir. Bubbles are a sure sign.

Get a Subaru thermostat or a Stant Exactstat. The cheapies you will have problems with. Pop it in and see how it does.
Read up on how to properly fill and bleed the cooling system, air pockets are guaranteed with these engines and need to be properly worked out or you will overheat.

#5 Marmaduke

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Posted 09 December 2013 - 10:55 AM

Do you guys think that the car would have made it to 170,000 miles with a blown head gasket? I know those are problems on the 2.5s, but that seems like a lot of miles to travel on a blown one. There is a newer plate where the head gasket is, so it looks like it has been replaced. Replacements will typically outlive the rest of the engine, no?



#6 86 Wonder Wedge

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Posted 09 December 2013 - 12:07 PM

Someone gutted the thermostat or removed it entirely, probably trying to cure an overheating issue, which on that 2.5 means head gaskets. While the engine is warm and running look for bubbles coming up in the overflow reservoir. Bubbles are a sure sign.

Get a Subaru thermostat or a Stant Exactstat. The cheapies you will have problems with. Pop it in and see how it does.
Read up on how to properly fill and bleed the cooling system, air pockets are guaranteed with these engines and need to be properly worked out or you will overheat.

 

Nail on the head.

 

Someone did the HGs, didn't bother to check for a thermostat/test it. OR they're not the revised HGs from subaru or Fel-Pro and the problem arose again and they gutted the thermostat.

 

Most likely the replacements would be Fel-Pro. Fel-Pros have a tab that sticks-up above the head-block mating surface that says "Fel-Pro" on the driver's side, just behind the dipstick, somewhat under the intake manifold. You can see it from the front of the motor.



#7 Fairtax4me

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Posted 09 December 2013 - 12:36 PM

Fel-pro replacements are still a MLS design just like what you would buy from Subaru. It's not so much the fault of the gasket these days as it is the attention to detail of the person doing the repair.
The MLS gaskets have to have a perfectly clean, flat surface in order to seal properly. And a lot of people just slap new gaskets and go rather than getting the heads milled like they should.

If someone did the gaskets, that doesn't mean they sealed correctly. Or they could have replaced the thermostat with a cheapo, or didnt put one in at all.
The thermostat is the first place to start since that's what regulates the temperature of the coolant. It's obviously not being regulated correctly, hence the wild temp guage.

Another possibility could be a loose connector on the temp guage sender. But I think the guage would be more erratic if that were the case.

#8 MilesFox

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Posted 09 December 2013 - 12:59 PM

i would imagine whomever replaced the HG omitted the thermostat to prevent overheats. But that doesn't accomplish anything.

 

Remember to fill the block via the upper hose before filling the radiator if you open the cooling system to inspect the thermo, and follow proper burping procedure.

good luck.



#9 Rooster2

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Posted 09 December 2013 - 10:42 PM

My 99 OBW made it to 192K miles before blowing its original HGs. Some 2.5 motors will make it that far.

 

Like others wrote, I immediately thought the thermostat has been removed from that car. I suspect the HGs are bad, but not terribly bad, so car driven easy doesn't over heat.



#10 Marmaduke

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Posted 10 December 2013 - 01:00 PM

Hey everyone, thank you for the replies. I dropped the car off at a mechanic I trust this morning, and am waiting with my fingers crossed for him to tell me it is NOT the HGs. I knew buying the car I'd have to throw some money at it, but I've been praying it's not a HG issue. How much did you all have to spend? I've been quoted anywhere from $1,200 to $2,500 for them to be replaced when calling around.



#11 amhawks

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Posted 10 December 2013 - 01:38 PM

@MammaDuke: I'm curious on how hot the car is getting?  You say they are going up, but how high on the gauge?  

 

@Everyone else who said HG's.  I'm not challenging you, but if it was HG's wouldn't the temp go up with RPM's (thus forcing more exhaust gas into the coolant)?  Or would the water pump spinning at a faster RPM suffice for cooling it to normal operating temp  (if MammaDuke's car is even in normal operating range).  Just trying ot put the pieces together in my head.  Thanks. 



#12 Marmaduke

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Posted 10 December 2013 - 01:46 PM

The car cruises at 80MPH right around the 3450 RPM range. At those RPMs, the temperature gauge stayed at at just under a quarter. When I downshifted to pass traffic, I revved it up to roughly 5500 RPM and literally watched the temperature gauge plummet to almost bottoming out on cold. Got back to cruising speed of 80 MPH, 3450 RPM, and the temp gauge slowly worked its way back to a tad bit under a quarter. Granted I was driving over Snoqualmie Pass (Washington State Cascades), and the temperature was probably around 3º F, I've driven over it in colder wx with no issues on different cars. As soon as I got onto country roads, doing 40MPH at 2500 RPM, the temp gauge worked its way back to half and stuck there.

 

Driving the car around town in normal conditions, the temperature gauge stayed right at halfway; no issues. Didn't matter if it was idling at a light, accelerating normally, or cruising at 25MPH.

 

I should also add that the car sounds healthy. There's a little bit of a rattle, but I think that's coming from whatever aftermarket exhaust is on the car (there's K&N stickers, but that may just be air filter).


The ONLY time it smelt a tiny bit hot is right after I bought it, I hit the redline in third gear. But the temperature gauge was normal, and the smell lasted maybe 3 seconds.


Edited by Marmaduke, 10 December 2013 - 01:48 PM.


#13 amhawks

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Posted 10 December 2013 - 01:57 PM

The car cruises at 80MPH right around the 3450 RPM range. At those RPMs, the temperature gauge stayed at at just under a quarter. When I downshifted to pass traffic, I revved it up to roughly 5500 RPM and literally watched the temperature gauge plummet to almost bottoming out on cold. Got back to cruising speed of 80 MPH, 3450 RPM, and the temp gauge slowly worked its way back to a tad bit under a quarter. Granted I was driving over Snoqualmie Pass (Washington State Cascades), and the temperature was probably around 3º F, I've driven over it in colder wx with no issues on different cars. As soon as I got onto country roads, doing 40MPH at 2500 RPM, the temp gauge worked its way back to half and stuck there.

 

Driving the car around town in normal conditions, the temperature gauge stayed right at halfway; no issues. Didn't matter if it was idling at a light, accelerating normally, or cruising at 25MPH.

 

I should also add that the car sounds healthy. There's a little bit of a rattle, but I think that's coming from whatever aftermarket exhaust is on the car (there's K&N stickers, but that may just be air filter).


The ONLY time it smelt a tiny bit hot is right after I bought it, I hit the redline in third gear. But the temperature gauge was normal, and the smell lasted maybe 3 seconds.

 

A Subaru should run at the halfway mark on the temp gauge.  It does sound like your t-stat is removed.  

 

That rattle is probably a heat shield, no biggie.  Most Subaru's have that signature rattle.

 

Best of luck and keep us posted on the diagnoses.   


Edited by amhawks, 10 December 2013 - 03:16 PM.


#14 Rooster2

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Posted 10 December 2013 - 02:26 PM

If you do replace the T-stat, install a good one, either OEM Subaru, or after market one costing about $30+ dollars. Cheap after market T-stats just don't work properly in a Subie. Lots written by others in the past on this forum about problems with a cheap T-stat.

 

If you do go to a parts store to buy a T-stat, ask to be shown a cheap one, and a top of the line unit. Comparing the two side by side,  you will see that the cheapie has a very short coil spring, vs the longer coil spring in the top of the line model. For what ever reason that short spring model won't open and close properly in a Subie



#15 Marmaduke

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Posted 10 December 2013 - 02:33 PM

The car is at my mechanic right now. If it's just the thermostat, I'll make sure they use OEM or the highest quality after-market available. I am usually leery of mechanics, but trust this guy and they warranty parts and labor for 12 months/12,000 miles. I'm in the process of moving across town, and it's already stupid cold and dark by the time I get off work so I'd rather just pay for them to do it.


Edited by Marmaduke, 10 December 2013 - 02:47 PM.


#16 Marmaduke

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Posted 10 December 2013 - 05:23 PM

Sorry for double post, but I though I'd update as the mechanic just got back to me. As for as the cooling issues go, he found the following:

 

Bad thermostat, and lower radiator hose leaking.

 

Upon further inspections he said the cam seals are leaking bad, which would be fixed by a new timing belt/water pump.

 

He said it has a bad CV boot, and needs a new steering rack as well.

 

All in all, I was quoted $2916.00, but he says the car should run for another 100,000 miles.

 

What do you guys think? I'm looking at being $6400.00 for the car at that point. I'll know it'll be good, but that's a LOT of money.

 

Should I cut my losses and sell it, or invest?

 

On the plus side, he thinks the HGs are good.


Edited by Marmaduke, 10 December 2013 - 05:23 PM.


#17 amhawks

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Posted 10 December 2013 - 05:50 PM

Sorry for double post, but I though I'd update as the mechanic just got back to me. As for as the cooling issues go, he found the following:

 

Bad thermostat, and lower radiator hose leaking.

 

Upon further inspections he said the cam seals are leaking bad, which would be fixed by a new timing belt/water pump.

 

He said it has a bad CV boot, and needs a new steering rack as well.

 

All in all, I was quoted $2916.00, but he says the car should run for another 100,000 miles.

 

What do you guys think? I'm looking at being $6400.00 for the car at that point. I'll know it'll be good, but that's a LOT of money.

 

Should I cut my losses and sell it, or invest?

 

On the plus side, he thinks the HGs are good.

Did he check the HG's and if so what test did he use?



#18 Marmaduke

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Posted 10 December 2013 - 05:50 PM

Not sure what test he used, but he said as far as he can tell, the HGs were done.



#19 Fairtax4me

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Posted 10 December 2013 - 07:33 PM

@MammaDuke: I'm curious on how hot the car is getting? You say they are going up, but how high on the gauge?

@Everyone else who said HG's. I'm not challenging you, but if it was HG's wouldn't the temp go up with RPM's (thus forcing more exhaust gas into the coolant)? Or would the water pump spinning at a faster RPM suffice for cooling it to normal operating temp (if MammaDuke's car is even in normal operating range). Just trying ot put the pieces together in my head. Thanks.


Head gaskets typically do cause overheating. What people do to alleviate the problem is often to drill holes in the thermostat, which can cause the behavior described by the OP, since the thermostat is no longer able to close and keep coolant temp up where its supposed to be.

#20 upnorthguy

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Posted 10 December 2013 - 10:04 PM

I don't know your level of wrenching, but if you have any mechanical aptitude, you could do a lot of those things yourself and cut that cost way down:

-The timing belt on that car is pretty easy and you can get a t-belt kit for that (includes water pump, pulleys and cam seals, tensioner) for about $216 on ebay.

-You can get a new half shaft for about $75, but most people here prefer to try and get an OEM half shaft from a salvage yard.

-OEM thermostat is about $25, gasket is another couple of bucks.  Two bolts and some new coolant and that is done (best to do this when doing the timing belt because the extra room gained with the radiator out is very helpful)

-I haven't replaced a Subaru steering rack, when I've done one on a Civic and it took some time, but was doable (I'm a driveway kind of guy working of jack stands in the cul-de-sac!).  Again, most here prefer to get an OEM rack from a salvage yard car rather than one from a parts store.

 

$2,900 is a lot of money to spend on a car worth a few thousand...



#21 AdventureSubaru

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Posted 10 December 2013 - 10:33 PM

Unless you're having issues with steering, I would ignore those for the time being. Put a good T-stat and rad hose in there and see how the engine does after a few weeks.

 

Steering racks don't regularly fail on these cars. I've personally never seen one go. And driving without power steering is no safety issue. If it's not life and death, worry about the rack at a later time. They can be had at a junkyard for about $50. and can be replaced in a few hours.

 

Cam seals - ignore them for now. Just check your oil levels periodically and top it off if it gets low. If the engine is A-ok after the T-stat and all - no bad head gaskets - then think about doing the timing belt and water pump.

 

Focus for now on being sure your engine is healthy. Doesn't make any sense to pay what the car is worth in repairs when headgaskets are still a concern/possibility.

 

Also - you can do any of the repairs listed with fairly basic tools in your driveway/garage and save lots of $$$$ in the meantime.

Don't rush into it and blow a bunch of money on a mechanic.



#22 Rooster2

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Posted 10 December 2013 - 10:57 PM

Unless you're having issues with steering, I would ignore those for the time being. Put a good T-stat and rad hose in there and see how the engine does after a few weeks.

 

Steering racks don't regularly fail on these cars. I've personally never seen one go. And driving without power steering is no safety issue. If it's not life and death, worry about the rack at a later time. They can be had at a junkyard for about $50. and can be replaced in a few hours.

 

Cam seals - ignore them for now. Just check your oil levels periodically and top it off if it gets low. If the engine is A-ok after the T-stat and all - no bad head gaskets - then think about doing the timing belt and water pump.

 

Focus for now on being sure your engine is healthy. Doesn't make any sense to pay what the car is worth in repairs when headgaskets are still a concern/possibility.

 

Also - you can do any of the repairs listed with fairly basic tools in your driveway/garage and save lots of $$$$ in the meantime.

Don't rush into it and blow a bunch of money on a mechanic.

+1 all that is written above. I could not have said it better. Suggest your immediate focus is on replacing the t-stat, and see where you stand.



#23 Marmaduke

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Posted 11 December 2013 - 12:17 AM

Thank you guys. You're making me feel a bit better.

 

If I can get good directions, I'm sure I'm capable of doing some of it myself. If all the steering rack is going to do is affect the power steering, then oh well. I don't care about that. I'm more concerned about quickly wearing through tires.

 

I think I may do the CV boot, and wait on the rest of it.



#24 lneulicht

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Posted 11 December 2013 - 07:36 AM

No need to do the CV boot until the axle itself goes bad, then replace the whole axle. It will start to make noise when turning and can run like that for quite a while..


Edited by lneulicht, 11 December 2013 - 07:36 AM.


#25 Marmaduke

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Posted 11 December 2013 - 11:14 AM

Mechanic said it would be cheaper/easier to do whole axle than just boot.







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