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Old 03-25-2009, 06:56 AM   #1
thoughto
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1998 Version 4 STI
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Default Coolant system V4 STI

I just bought my car. The day I got it home a coolant hose sprang a leak. The coolant system was corroded, so I used Holts Radflush 2 step system to clean it out. Then another hose sprang a leak. I noticed the metal line across the top of the rad to the coolant overflow bottle was blocked with corrosion. It even had a small hole in the middle, but nothing ever came out so I know it was blocked since I got the car. I got a new metal line.
I have a couple of ques.
1. The overflow bottle has a rubber hose off it into the fenderwell. Does this lead to another bottle?
I cleaned this part out with a hose, and refilled the overflow bottle with clear water. The rest of the system I refilled with coolant, burping the 2 big rad hoses many times. I went for a drive and tried to see if the coolant made it across the pipe into the overflow, but so far inconclusive.
2. Do you have to thrash the engine severely to get the rad cap to open the overflow line?
3. Would I be seeing bubbles in the overflow bottle if the car had a head gasket issue?
4. Should the big rubber hoses still be easy to squeeze when the car is up to temperature, or should they be quite hard due to normal pressurisation?
Thinking of buying new rad cap, thermostat, radiator and coolant hoses.
Sorry for long post, thanks for any advice!
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Old 03-25-2009, 08:46 AM   #2
Jaxx
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1 no it is drain
2 no
3 maybe?
4 they get hard

you need to add a water pump to your list if every thing else was that bad the water pump is too .. to me the radiator would be the lowest thing on that list .. you should be able to get it flushed/cleaned vs replaced
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Old 03-25-2009, 10:50 AM   #3
linsavy
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Just to add a little... there are 4 more rad hoses that flow between the turbo, reservoir and IAC. You might want to replace them as well. I have seen complete sets for sale on ebay for about $100, but I can't vouch for the quality.
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Old 03-25-2009, 11:10 AM   #4
thoughto
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Thanks very much for the replies. It looks like I just had a third hose go, coming home from lunch the temp gauge started to climb a lot. I suppose this time it was a hose underneath somewhere, as there wasn't much visible sign except the gauge going up. I really have to figure this out. Is changing the water pump the same as it would be for a WRX? I have the manual pages for that, but the Japanese model manual pages I have found are not so helpful. Please let me know if there is a good resource for this type of info (PM is good). I can get a set of 7 Samco hoses for my car for 65, which is below the dealers cost (although there are probably supposed to be 8 hoses and one is missing). There are some ebay UK shops that are fairly reasonable, but a water pump is still 40. Would a water pump gone bad explain all my symptoms? Also I better get to the drain for the coolant bottle and unblock it.
OK, thanks again guys, will keep struggling on, Tom
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Old 03-25-2009, 11:32 AM   #5
linsavy
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Yes a bad water pump would explain the overheating, so would poor flow from clogged rad and hoses. The degunking flush may have cause more problems due to loosening gunk that went around to clog stuff. Your cooling system sounds really bad from your descriptions. If I were you I would change the water pump, change the rad cap, check the thermostat and change all those hoses. I would probably do the rad too.
These cars are difficult to burp all the air out. You could just have an air pocket. You need to put a funnel in the reservoir pot by the turbo and fill it will coolant. Run the motor until the t-stat opens and squeeze the upper rad hose. Burp out all air for a few minutes.
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Old 03-25-2009, 12:30 PM   #6
Jaxx
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annnnd (you probably won't like this) if you have the timing belt off for the water pump ... you should replace it and the tensioner and pulleys too ... there should be a silver sticker on the timing belt cover when the belt was last changed..
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Old 03-25-2009, 03:09 PM   #7
thoughto
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Thanks again. The hose which went this time is not an easy one to find. It appears to be on the driver's side (left on a JDM, as you face the front of the car) and is not one that connects to the turbo coolant reservoir or one at the top of the engine. Until I buy jack stands (I just moved to the UK, that's why I dont have them) and can get under the car I'm not sure I can figure out where the new leak is. It is clearly a big hole or a hole in a big hose, as it seems to drain a lot quicker than the previous leaks. The oil still looks OK on the dipstick, and the coolant doesn't look oily. Can you suggest where the leaking hose might be, if one is more likely than others? The coolant mainly leaks down under the up-pipe and manifold on the left, that's all I can see for now.
The silver sticker says 93,557 km which corresponds to less than 12,000 miles ago, so I'm hoping that is fine. The 2 other numbers on the sticker are 19/24 does that mean something?
To change the water pump is it necessary to actually remove the timing belt first, or do you just slacken an idler pulley then retighten? I am getting a bit out of my depth here.
Thanks, Tom
One very simple thing. I noticed that the rad cap is very difficult to tighten and to remove - it takes a lot more force than my previous WRX one. The label came off, and I notice that the central "button" does not rotate as the cap rotates, but remains in its original orientation. Does that mean anything?
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Old 03-25-2009, 03:58 PM   #8
linsavy
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Is the leaky hose connected to the turbo? One goes in and one goes out.
You need to remove the timing belt and recompress the tensioner with a vise. You might want to make one of these handy tools to hold the cam gears.
http://forums.nasioc.com/forums/show...g+belt+install
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Old 03-25-2009, 04:47 PM   #9
thoughto
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The leaky hose isn't the one from the turbo reservoir "downwards" to the turbo (that one was the second to be replaced). Will look again for the other one connected to the turbo, but I had the feeling the leak was lower in the engine bay, if that makes sense?
Couldn't seem to see the "handy tool", I think the pics have been taken down. Looks like some locals here may give me a hand, which would be fantastic. Thanks, Tom
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Old 03-25-2009, 09:13 PM   #10
i_c_the_light
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You might want to add a new cap to the list of things to replace. Lord knows what state the header tank is in.
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Old 03-26-2009, 04:13 AM   #11
thoughto
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Well the header tank was the thing I spotted first. As soon as the first hose leaked I took that off the car, took it apart, and was surprised how corroded it was, especially compared to my 2002 WRX. That's when I bought the stuff to flush the system with. I used some of the flush stuff to attack the corosion on the header tank, and definitely improved it a lot. I will have another go at the top part today, and try to fix the block in the drain from the coolant overflow. I hope that rubber hose is easy to find under the wheel arch.
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Old 03-26-2009, 10:49 AM   #12
Jaxx
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well i suppose the other thing you could do is to fill with 100% water let it circulate then pull the lower hose (don't let it get too hot) and let it drain ...repete as many times till it clears all the gunk out
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Old 03-27-2009, 06:21 PM   #13
thoughto
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linsavy you were correct about the latest victim hose. Hard to spot as it was covered in some sort of heat wrap. I got a new rad cap. WHat I started to think was that the centre section of the rad cap might need to be in a certain orientation for the overflow pipe from the turbo reservoir to function. My centre section was rotating independently of the outer section, and so the holes might not line up? Does that make sense to anyone? The new rad cap's centre secion is fixed, but the "hole" in the centre section appears to face the opposite direction from the hole for the overflow pipe. Does this mean anything or should I put up a picture or does the orientation not matter? Rad cap screws on much easier anyway.
The other thing I want to fix is the blocked drain hose from the overflow bottle. As I said, this disappears into the fenderwell / wheel arch, and I can't seem to get at the blockage. I've busted a few plastic clips and tried to free up the black plastic wheel arch liner but it is a lot tighter than my old WRX. Does anyone have a good trick to get to the exit of this drain hose and unblock it? Thanks for any advice, hoping to get somewhere tomorrow.
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Old 03-29-2009, 02:35 PM   #14
thoughto
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I am resigned to replacing the water pump and thermostat. I put the hoses back in and ran the engine starting with cold water. The water in the turbo reservoir became hot very quickly, while the water under the rad in the hose used for burping remained cold for a long time at idle. The temp gauge went up close to the middle range, but with the heater on full no hot air came out of the vents on a coldish evening here until I gave up the experiment (must have been 10-15 mins I guess). Then when I drained the system cool water came out followed by hot, followed by cool then hot etc - it just seemed like the water couldn't possibly have been circulating properly.
So I'll buy the water pump and thermostat, and try to find the best instructions for this job I can, with plenty of pics, and see if I can find a local with experience to help a bit.
linsavy: you say "You need to remove the timing belt and recompress the tensioner with a vise." This sounds scary to me. Until I get the belt cover off I can't really imagine what this is going to be like, but using a vice on a tensioner sounds rather risky, like I might break something or get the tension wrong. If you would point me towards the best method with pictures that would be great.
One other thing, on the V4 STI there is a hidden reservoir for coolant in the wing of the car. This is where the rubber hose from the coolant overflow bottle goes. I got really stuck trying to get the wheelarch liner loose so I could take a look at where the hose goes, but I got a printout of the cooling system from a better manual page (all in Japanese) at a dealership, which shows this. I also had a reply on a UK website from a guy who had replaced his wing and who had found this hidden reservoir. Perhaps this piece doesn't come with some of the version 4 engines that are imported to the US.
Thanks a lot, Tom

Last edited by thoughto; 03-29-2009 at 02:37 PM. Reason: spelling, grammar
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Old 03-30-2009, 10:40 AM   #15
linsavy
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thoughto - you might as well get a new timing belt tensioner, they are not really expensive. The old style one can be compressed, just do it very slowly, like take 2 minutes to do it. Put a pin/nail in the little hole to hold it down while you re-install.
The orientation of your rad cap doesn't matter.
All v3 and V4 have the overflow bottle that hides in the fender I believe. Don't bother trying to get at it as I doubt it is the cause of any of your issues. Go with the water pump and new T-stat.
There are write ups on this site with pics and part numbers for the t-belt and tensioner. It is the same set up as for DOHC legacy motors (ej25d) look up 97-99 Legacy. search for "DOHC timing belt"
You can do the t-stat first. Try taking it out all together, reassemble, fill with water and run the motor without it in the housing. Or you can boil it on the stove and see if it opens OK.
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Old 03-31-2009, 08:47 AM   #16
thoughto
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So I drained the car, took out the thermostat, put it back together (reusing the gasket that fits around the thermostat as I thought it would leak otherwise), and filled with cold water. When I started up I was very pleased to see that the water in the rad bottom hose quickly became warm, nearly as warm as the top hose. The turbo reservoir didn't get really hot nearly as quickly as before. And when I revved the engine water seemed to get sucked down form the turbo reservoir. All of these things indicate to me that the water pump is OK.
I put the thermostat in a saucepan of water and heated to boiling. It did open, but only when close to boiling. I wasn't sure what to expect, and was a bit disappointed it did anything at all, but maybe it is just too slow?
Anyway I have a new thermostat coming before 1 pm tomorrow, and I'm really hoping that is going to stop my exploding hoses problem. Meantime I think I'll do the 2 step flush again. There is still some corrosion knocking around, and if the water didn't circulate well last time I did it I'm sure it didn't work properly. A UK guy suggested to me that a mechanic told him that those flushes should be done without a thermostat present, and it makes sense to me as that way the coolant is always circulating well, although I guess it won't get so hot.
I don't suppose it's a good idea to drive without a thermostat, eh?
Thanks again everyone who's helped, I hope I'm nearly out of the woods. Tom
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Old 03-31-2009, 09:24 AM   #17
linsavy
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you can drive without a thermostat. It will just take a long time to warm up and you will use more gas until it does. Stay off boost until it's warm.
The t-stat should open wide at about 70C
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