Overheating STi

[Red Baron]

Right Chaps, as some of you know my brother has recently bought a JDM Bug STi with a knackered bottom end. A replacement engine was sourced and fitted this weekend which benefited from new Cam Belt and tensioners, plugs, rocker cover gaskets, crank shaft oil seal and a clutch change while it was easy to get at everything.

The replacement engine (which was sourced from a reputable breaker who ran the car for a week before breaking) runs fine but from the moment it went in has been blowing water back into the header tank and overheating. The engine does not over heat if you drive it off boost or leave it on tick over all day but as soon as you give it boost it blows all the water into the overflow bottle. He's bled the entire system repeatedly and changed the thermostat, he's also had a sniff test done twice to see if the head gaskets have gone and they both had negative readings for exhaust fumes. Has any body come across this before? The other engine had not overheated before so there was no cooling system issues before this engine. There's a new water pump going in today just in case the impeller is spinning on the shaft under load.

I've posted pics below of the engine just in case anyone can spot something obvious that has gone back out of place or has been swapped.









Cheers, Shane and Toby

[SpecB]

Hate to say it, those are the exact symptoms I had and when the heads were pulled there was an obvious leak path from the bore to the water jacket evident on the HG.

One other test to do (sniff tests are unreliable) is to run the car up to temp with the expansion cap off so the system is at temp and not under pressure. Then fit the cap, if the system then pressurises significantly you have a leak!

If you're lucky you're just rubbish at bleeding the system! It took me 3 goes once!

Have you tried the fill via the top rad hose method?

[Red Baron]

Head Gasket was obviously our first thought Nick, especially after reading about the symptoms you and Steve had. Water pump is being done today and I'll get him to try the method above if he hasn't already.
The engine supplier is still on board with us at the moment and hasn't washed his hands of the whole thing but it's still frustrating as it will be an engine out job again having just spent a weekend swapping them.

[C. J.]

I'm sure it won't take a weekend next time , 5 to 6 hours I'd guess as your know where your going
You changed rad cap ? Could be as simple as that or trapped air , heater on hot when filling ?

[Red Baron]

Took longer as had to get the cam belt covers off the old engine as the one on the new engine was damaged in transit so it was little things like that which slowed him down, and the fact it was the first time he'd done one.

Pretty happy that all the air is out of the system, sure he's done the rad cap but I'll check.

[Red Barons Brother]

Hi guys thanks again to my bro next time we meet up I will get him to show me the whole photo upload thing any way have bled the thing a million different ways that you can think of and there is no air in the system the heater works fine the engine does not overheat (obviously it would if I kept thrashing it about every where but I always stop before then)I don't think it is the water pump but have to try it to make sure. The engine did sit without water in for a month but can't believe this caused any problems?

[Red Barons Brother]

Just seen the rad cap thing I have replaced it and the system holds 1.2 bar of pressure before it blows off.

[C. J.]

Sounds hg then

[oldskool]

Sorry to hear this ,, what a pain

I can vouch that sniff tests aren't the most reliable things as my previous car ( non scooby) passed two when i suspected there was a problem ,,, despite passing them i was certain i had issues and sure enough when we took the head off the hg showed clear signs of failure and once replaced the symptoms i had picked up on were all cured

Not saying your headgasket is gone but can definitely confirm sniff tests are not to be relied on

[Red Baron]

A quick update, as we thought, the water pump made no difference at all, the person who supplied the engine is collecting the entire car on Monday and has said he will fix any problems before returning the car by the end of the week, will keep you all updated.

Shane

[Scott.T]

Originally Posted by Red Baron

A quick update, as we thought, the water pump made no difference at all, the person who supplied the engine is collecting the entire car on Monday and has said he will fix any problems before returning the car by the end of the week, will keep you all updated.

Shane

Nice one
Matty desrves a pat on the back for customer service if he sorts it.

[RobEvo5]

On Boost overheating is the same problem, I had with a Celica GT4 I had and after a strip down transpired in to be a cracked cylinder bore.

[Red Baron]

Toby noticed one of the head gaskets had already been done, we obviously don't know how long ago this was though.
Mattys feed back on Scabbynet and even Ebay are faultless, this why he chose to pay a bit more for an engine from a reputable source, hope he can fix it easily, there's a few quid invested in that engine already.

[Red Barons Brother]

So let's see what they come up with I tried everything so I know it is not a fault that I have done even though the car forces water back out it has to this date never overheated as I have always stopped the car before this happens (I am lucky to have lots of private tracks outside my house so don't even need to go on the road to test). I hope for their sake it is something simple but I would think not. Again thanks guys and I will let you know how we get on.

[Red Barons Brother]

So just to keep every one up to date the ENGINE SUPPLIER now has my car and we are at the agreement that if it is something I have done (which I know I haven't)I will pay and if it is the engine he will pay. He has now come to the conclusion it is engine based and has removed the engine and striped the heads off. He says he can't find any faults in the head gaskets and is having the heads pressure tested but I will not know the answer until after the weekend now. He is just as baffled as myself. He did find a lot of gunk in the expansion tank and in the coolant pipe to the turbo but has said they were not blocked and would not have caused the symptoms I have. (Just like to say have had both of these items off during the engine swap and did not find anything in them) So if the heads come back fine he will have to look into a crack in the block, fingers crossed for me that he finds something engine related as this could become expensive otherwise. All this said the ENGINE SUPPLIER has been very helpful,understanding and polite. I will let you know how I get on next week as I am sure everyone wants to know the answer.

[Ginola]

Looking forward to knowing what the actual problem was, keep us posted dude.. I will grill Shane on Sunday for more of the low down

PS.. how is Ascot?

[Red Barons Brother]

Cheers Dave was hoping to be there on Sunday but obviously not now. I cant even bring my BMW as the clutch went last week and has now run out of MOT so I am not having a lot of luck with cars at the moment. Anyway hopefully be at the next meeting in a Subaru. Ascot is good I live right on the high street and my wife is already fed up with me shouting Subaru everytime I hear one drive past lol. Congrats to the whole moderator thing.