Scoobykyle07

Just changed the radiator for a new mishi moto one and since burping the system the temperature seems to creep up under boost. Normal temp when cruising but as soon as I give it some it goes up? Changed and burped the coolant? Any ideas what can be causing this? Been told could be the thermostat or a possible water pump? Any ideas would be perfect. Thanks in advance all!

Vxr2010

Use your original scooby rad caps , the pressured spring one on the pressured expansion tank , the solid non spring one on the rad , known issues with Mishimoto caps 👍

Scoobykyle07

Thank you mate, thing is that when I got the car it had buddy clip caps on the rad and tank? What’s your thoughts on that? As you can tell this is my first scooby

Vxr2010

If it was working with the previous caps and no getting hot issues that's fine , just make sure the spring cap is on the pressured header tank , the pressured header tank is the one over the top left of the engine as you look from the front of the car , and non spring cap on the rad , that should sort it , fingers crossed 👍

Scoobykyle07

Legend! I will give that a bash and see if that makes any difference. If it’s not sealing though wouldn’t that cause the coolant to leak out?

Vxr2010

Bleeding wise , when cold , fill the rad , put the cap on , take off the header tank cap , put coolant in but don't fill to the top , start the car , if there are bubbles then there is still air in there , keep topping it up , as the bubbles allow space to top it up , but don't fill to the top , once the coolant starts over flowing cap on , then recheck both caps and the non pressured expansion tank once it has fully cooled down ,

Vxr2010

Sorry missed that , what's not sealing ? , if the system is not pressurised yes it will be more likely it to boil over

Vxr2010

Both the caps that subaru do are different some in error put the wrong cap on the wrong bit ie rad cap on header tank and visa versa

Scoobykyle07

I will give that a try, is there a certain coolant I should use? Previously it had green and I changed it to blue mpm antifreeze (low phosphate)?

Scoobykyle07

If the caps not sealing properly… also sounds strange but when I boost it I can smell coolant?

Vxr2010

I take it you had no cooling issues before fitting the Mishimoto rad , if it's leaking from one of the caps the coolant temp will go high , as when under pressure it raises the boiling temp , the way the post reads from what I understand is the issue started when you fitted the Mishimoto rad , if that's the case then check you have the right cap in the right place , and I personally use the standard subaru caps , I don't know much about your original caps not heard of them before , but if the original caps you had were working and no over heating issues then re use what you had 👍

Vxr2010

I tend to use red coolant , don't mix coolants red with red etc 👍

Scoobykyle07

Originally I could smell coolant constantly then I blew the rad so replaced it with the mishimoto 1

Vxr2010

So if you are smelling coolant all the time then a leak , any signs of where the leak is ? Worth changing the caps in case ones not sealing as they can fail over time , and then try a re bleed , if the hg has gone then the non pressured expansion tank screwed to the rad on the right side of the car , it will have a constant stream of bubbles , 2 litre or 2.5 what sort of mileage ?

Scoobykyle07

I only smell coolant now when I give it the beans, the original rad was leaking at the top and the top hose from the rad had a split in it so that’s why I changed the pipes and rad. I was thinking hg but the last owner had the engine rebuilt at 47k miles and now it’s on 71k… 2.5litre

Vxr2010

If it was me , new subaru oe rad caps , give it a full proper bleed , then see if it's still doing it , even if well re built still a risk of hg issues

Scoobykyle07

Yes I will call Subaru and get some genuine caps sent out. What’s your thoughts on it being the thermostat? Might also replace that?

Vxr2010

Stat wise when it warms up does the rad warm up evenly ? if pump is working , when cold look in the pressured expansion tank and you will see the coolant going round , I personally have never had a pump or stat fail on a car , does not mean they don't , import car parts will post out or main dealer for the caps , sniff test , but I have always found the constant bubbles in non pressured expansion tank as the best indicator , when you bleed it you will get some bubbles but once bled should be not constant bubbles 👍

Scoobykyle07

Me an the local mechanic have bled the system and there’s no bubbles from the expansion tank, rad or overflow tank that’s what’s confusing as don’t really know where to start?

Vxr2010

Check the water pump is working , make sure the rad once it's up to temp that the rad is an even heat , and or just put a new stat in , a rad or expansion tank cap , if it's not keeping pressure could be your issue , sniff test , the fact you don't have a constant stream of bubbles is a good start , there was a track car that I heard of only over heating on boost as head was lifting slightly , and see where you go from there 👍

Scoobykyle07

Top man, I will give that a bash starting with the cheapest stuff first an see how we go

Vxr2010

Fingers crossed it's not hg , other things can cause the same issue so hopefully something simple 👍

Scoobykyle07

Fingers crossed 🤞 might just do the hg an get an upgraded gasket as well as better head bolts.

Vxr2010

I would not , only do what you need to do , hopefully it's a simple fix , if it's hg then do hg but it's ££

Scoobykyle07

True, just want the car to be mint and be able to enjoy it and not be constantly watching the temp gauge 🤣

Vxr2010

I get that , and yes that's frustrating , no point spending a load of ££ till you know what's what , im sure you will get to bottom of things 👍

Scoobykyle07

Appreciate you taking time out to share some advice. Thank you mate

Vxr2010

No problem , hope it sorts things , fingers crossed 👍 update when you know more

Scoobykyle07

Will do mate 🫡