Jump to content

My Subaru overheats. Why?


Simon2015
 Share

Recommended Posts

Hi everyone,

I have a 2008 b3 hatcheck that overheats.

The coolant temperature warning light starts to flicker when I go up hill. I also noticed that if I drive at HIGH rpm it happens LESS. I've replaced the radiator and the thermostat and it didn't help. I did a head gasket pressure test and no leak was found.

The mechanic at the garage said that it might be the head gasket although the test was fine. He says that it might be leaking only when the engine is working really hard and that is why he could not detect it in the test.

Replacing the headgasket costs lots of money.

I think that since the engine overheats less when I drive on high rpm, it could be the water pump (broken wings)?

Thank you guys.

 

Link to comment
Share on other sites

Hi guys, 

While I'm waiting for the sniff kit from eBay I have some more infortmation to tell you.

I checked for residues in the header tank and in the radiator cap.

The radiator was pretty clean but the header tank had some sort of mud on the walls yet it didn't really felt greasy or oily, just mud.

I tried to run the engine for 10 minutes at low rpm (0.5) then 5 minutes on 2 rpm then 5 minutes at 3 rpm and finally another couple of minutes at 4 rpm (was pretty noisy) and nothing happened. No blinking light and no movement of the coolant level in the header tank.

But earlier this day I drove up a steep hill for some time then the temp' light began to blink so I stopped and checked the coolant level and it was over flowing.

I don't get it. What happens when I go up hill that doesn't happen when I'm just revving the engine. Maybe I didn't rev it for enough time?

Link to comment
Share on other sites

Early symptoms of headgaskets on boosted cars somtimes only happen when at 1/2 + throttle (when on boost) as there's much more pressure in the cylinders causing it to squeeze past the failing gasket (which eventually completely blows)

The boxer layout (especially in open deck form) normally pushes combustion gasses into the coolant creating creamy grey foam and bubbles in the header tank .

Rather than the usual oil and coolant mixing together that is the norm for straight 4 engine configuration

id imagine the engine would be under a much greater load when pulling the weight of the car uphill than just rev'ing in neutral, hence why it was worse going uphill

  • Like 1
Link to comment
Share on other sites

Thanks man,

when the coolant overflowed today it looked usual, it was hot but there was no foam or bubbles.

If I keep driving this way, can I damage something other then the head gasket ?(that I am going to replace anyway I think) 

Link to comment
Share on other sites

Unfortunately yes , most reputable subaru specialists recommend getting the bottom end refreshed when a replacing a headgasket while the engines out anyway .

As the pistons trying to combust coolant and the overheating can cause a lot of extra strain on the bottom end ,causing the bottom end to fail once the headgaskets have been replaced and the cars given back to the customer.

Although some garages will replace just the headgaskets and the engine might well be fine but if it's not and goes bang their reputation could take a battering so i think thats why most say to refresh the bearings too [emoji6]

Link to comment
Share on other sites

Yes and no really... The bottom radiator hose should be cooler, as that's the way the coolant flows through the radiator. But to me, cold would suggest it's not flowing through the block. I'd get your water pump checked.

Sent from my iphone using Tapatalk

  • Like 1
Link to comment
Share on other sites

sounds same as my hatch was doing,if i left it ticking over on drive it was ok,if i reved it on drive was ok,if i drove like a granny it was ok but if i put foot down all the coolant went straight in overflow tank and over flowed it and made temp gauge go straight up,i was driving 5 mile to work then having to empty overflow back into the header tank to drive home.i tried getting air out every day,dint seam to make any diffrence,so i change the cap on the header tank and that was it,problem gone,1 other thing dont over fill the other flow tank,i check mine when came home the other day and it was 3 quarters full them system suck't it back threw to were i had it originally at the low mark on bottle,am guessing if you over fill it then it will over flow.so i'd check air lock and get new caps see if that fixs it,it work for me.

Link to comment
Share on other sites

Thanks  aucky!

In my case it is a little different because it mostly overheats when I am at LOW rpm driving up hill. When I rev it going up hill it happens less. It seem to happen when the engine is really strained. I bet it is much harder for it to go up at low rpm. But,

 

I  finally did the sniff test and there is no sign of any leak!

I tested it on parking and it was good and a couple of minutes after overheating and it was also good.

The problem is that I can't do the sniff test right at the moment that the engine is hot (the moment I suppose the hg is leaking) because the coolant is at the top of the header tank and I need it to be a few inches below to preform the test.

 

What do you guys think of it?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share




×
×
  • Create New...




Forums


News


Membership