EJ25D Head Gasket Replacement

[99gtlimited]

So I'm going to be replacing the head gaskets on my '99 2.5GT, and I wanted to see what else you all would suggest to replace while I have the engine out. I have done plenty of reading, have both the FSM and Haynes manual, adequate tools, and a decent level of expertise. The engine is being taken apart for the first time as far as I know, and has 81K miles. The engine barely overheated only once, but sure enough there was oil in the coolant and bubbles in the overflow tank. This is what the coolant looked like after being drained

https://sl-i.net/FORUM/images/imported/2010/07/0706001834-1.jpg


Here's what I'm planning on replacing/inspecting so far:

- Head Gaskets
- Most other gaskets, filters, and seals that are accessible without splitting the block (valve cover gaskets, rear/front oil seals, etc.)
- Oil separator plate (if plastic and or/leaking)
- Clutch, pressure plate, throw-out bearing, pilot bearing
- Cylinder head and shortblock inspection


Here are some things I'm not sure about, I had the timing belt done shortly after I got car. With 55k miles the following was replaced :
- Both radiator Hoses
- Timing belt and tensioner, all timing belt idler bearings,
- Water pump and thermostat
- Resealed oil pump


I don't think I'll need new radiator hoses, but what of that other stuff should be replaced? It's only been 26k miles since it was all installed. Is it ok to re-use the t-belt and tensioner?

Should I pull and flush the radiator? or should I just wait and flush the system when the motor is back in?

Thanks for the input everyone!

-justin

[Reason]

Timing belt, all the T belt pulleys and tensioners. I would do the hoses too if you have the money and havent replaced them yet. Get it all out of the way since you are doing it now. Look at my build when I replaced all that crap, because I didn't want to have to do it again. I'll sell the car before I'll ever have to touch the motor again... Then again I do want to replace the block for a 2.5 so...

[99gtlimited]

The hoses are definitely ok, no need to change them. You think I really need to spring for the whole timing belt kit again even though it was all replaced about 25k ago?

I just want to know for sure before I drop another $300 for this build...

[decke48]

do all the seals you can do without spliting the block. reseal oil seperator plate (replace if plastic to aluminum one). R&I all the stuff you did at 55k make sure the tensioner is good, bearing spring freely, timing belt for oil and cracks/damage, check water pump for free spining and weaphole is clean and not leaking, check hoses, make sure not soft, or pitted/corroded inside. R&R whats needed.
thermostat is probally ok, i would replace it for safe measure, not expensive either, or at least get a new gasket

[Reason]

Yea if it was just replaced check it out then.

[ouch1011]

If you do reuse the t-belt (which I typically don't suggest) make sure to mark which direction it was installed on the engine. Put it back the same way. Pulleys and idlers should be fine, but spin them to make sure they are tight and quiet.

If you plan on keeping this engine for a looooooonngg time, you may consider having the heads rebuild while they are off. Yes I know, 88k is low mileage, but it is 11 years old, and seals (like valve seals) wear with age as well as mileage, and low mileage often means short trips, which is harder on an engine than longer trips resulting in higher mileage. At the very least, check them for warpage. You can do this yourself if you have a precision straight-edge (not a ruler) and feeler gauges. Otherwise, have a machine shop check them, should be really cheap (takes about 1 min per head).

Definitely flush the radiator and the heater core. Thoroughly. If you had oil in the coolant, that's bad. Oil will coat everything and make it less effective at transfering heat (which will cause the engine to overheat) and oil will break down the rubber hoses and make them fall apart from the inside out. I'd suggest replacing the hoses personally. If you don't, they need to be meticulously cleaned to get all the oil out.

[99gtlimited]

If you do reuse the t-belt (which I typically don't suggest) make sure to mark which direction it was installed on the engine. Put it back the same way. Pulleys and idlers should be fine, but spin them to make sure they are tight and quiet.

If you plan on keeping this engine for a looooooonngg time, you may consider having the heads rebuild while they are off. Yes I know, 88k is low mileage, but it is 11 years old, and seals (like valve seals) wear with age as well as mileage, and low mileage often means short trips, which is harder on an engine than longer trips resulting in higher mileage. At the very least, check them for warpage. You can do this yourself if you have a precision straight-edge (not a ruler) and feeler gauges. Otherwise, have a machine shop check them, should be really cheap (takes about 1 min per head).

Definitely flush the radiator and the heater core. Thoroughly. If you had oil in the coolant, that's bad. Oil will coat everything and make it less effective at transfering heat (which will cause the engine to overheat) and oil will break down the rubber hoses and make them fall apart from the inside out. I'd suggest replacing the hoses personally. If you don't, they need to be meticulously cleaned to get all the oil out.

The engine only has 80k, not 88k, but I do understand the need for inspecting the heads. I do have new valve seals, so if needed I will replace them. I plan to take the heads apart and inspect each component, as well as inspecting the heads themselves for flatness.

looks like I will most likely be replacing at least the Timing belt as well, and possibly the tensioner as well.

any other suggestions from all you out in legacy/subie land?

[Kuppa]

if your doing HG u might think about getting the valves reshimmed and ground since they arent hydraulic im going to be doing my HG and the tech i talked to said since im at 140k i should do the valves to. I know your not there yet but Y not if u can i guess