This is how I rebuilt my 4 cylinder turbo 4G63 cylinder head.

Not too long ago I had a 4G63 cylinder head with valves that were leaking like crazy. I pulled the head from the block and found the most carbon build-up that I have ever come across. The solution – rebuild the head of course!

I began by removing the stock turbo 4G63 cams.
Camshaft removal

I then organized all of my lifters and rockers, because keeping the parts in the same spots is ideal.

Each valve spring is held in with two “keepers”. Over time, the keepers become stuck in the spring retainers. If you tap the spring retainers with a socket, it shocks the keepers, and breaks them away from the retainers. This makes your life much better.

4G63 heads require a special valve spring compressor tool. I didn’t take a picture of it for some reason, but the moral is – you need to remove the keepers from all of the valves.

Don’t forget nourishment. Your body needs it if you want to be at the top of your game.

For fun, look at the valves in cylinder #1

Now look at them opened

Look at the valves in cylinder #2

Now look at them opened

Look at the valves in cylinder #3

Now look at the opened

Look at the valves in cylinder #4

Now look at them opened

Pretty bad carbon build up, don’t you think?

This is what they look liked before I cleaned them with a wire wheel.

This is what the valves look like after the wire wheel (same valve!).

Once cleaned, each valve needs to be lapped into the seats with valve grinding compound.

New valve seals should always be installed, because they are cheap, and you are already this deep into the repair.

I like to test the valves to make sure they hold water. If they hold water they should hold air just fine too. If the water leaks out, then you have a damaged valve or need to lap the valves better. In my case, I had 2 valves that were damaged beyond repair. The other 14 were A-okay!

Almost ready to reinstall!

Lastly, everything needs to be torqued properly. Make sure you use a good torque wrench because this is one of the times it really matters.

And that is what it’s like to rebuild a 4G63 turbo cylinder head that is packed with nasty carbon build up. The whole project was pretty cheap (less than $50), and took a few hours. Next time, maybe I will clean off my work bench first so that I don’t look like a car-part hoarder.

Subaru Valve Adjustment Tool / Valve Bucket Clearance Guide.

Subaru Legacy GT Limited_7

Imagine for a moment that you own a Subaru Impreza WRX, Legacy GT, or Forester with the EJ25 2.5L DOHC Turbo engine. Life is pretty good right?  Right! Until your valves burn, and you lose compression. Yeah having a Subaru with low compression is basically a death sentence because the cost to repair it is massive. The engine has to be removed, heads have to come off, be rebuilt, and the list goes on.

Alas – there is good news for the Subaru enthusiasts that are taking on this repair themselves and need to figure out valve clearances. I did this repair a while back and quickly realized that my feeler gauges were not metric (because they were ancient), which caused some challenges for the metric valve bucket sizing. So I made an excel file that converts inch sizes to metric and vice versa.  It also lists all of the valve bucket part numbers so that you can order the proper sizes for your car.  Oh, and I also included the Subaru valve clearance tolerances that were correct for my 2005 Legacy GT Limited. I’m not sure if they are the same for all Turbo DOHC EJ25’s or not. Do some research and use your best judgement!  Below is a download link to my excel file tool that you will find helpful if you are measuring Subaru valve buckets.


Good luck and post any questions below!

Got Waste Oil? – Put It In A Laundry Detergent Bottle.

Don’t know what to do with your waste oil? Well here is a tip for those of you that have tipped over and overfilled single quart oil containers. Don’t make a giant disaster with your waste oil before returning it to the store, pour it in a laundry detergent bottle! Here is why:


Anyone that does laundry probably has one (or more) of these bottles around. They are awesome for holding oil, antifreeze, ATF, etc. Not only are they usually a gallon or more (AKA – a full oil change on most vehicles), but they have a no-drip spout area.


Using a detergent bottle to hold waste oil means that you don’t need to make a giant disaster in your driveway pouring the waste oil back into those silly little 1 quart containers. Seriously, how many of those have you tipped over when filling them? It flat out sucks when that happens. The only thing worse is when you overfill them with a funnel. You know what I’m talking about… Using a laundry container also allows you to stuff the whole drain pan into the top of the detergent bottle, rest it against a wall, and walk away. When you return a few hours, days, or weeks later, your drain bucket is nearly oil free. Sweet right?


4G63 Wiring Diagrams / Schematics For Engine Swaps


1990 DSM 4G63 wiring diagram

1990 DSM 4G63 Wiring Diagram

1991-94 DSM 4G63 wiring diagram

1991-94 DSM 4G63 wiring diagram

One of the great downfalls of the common 4G63 engine swap, is that so many people begin them and never finish. It seems that enthusiasts spend endless money gathering parts and information, they get the engine installed in the vehicle, begin the wiring, and promptly throw in the towel. The vehicle then gets parted out and the engine swapper moves on to something else. I have seen this around 6000 times, probably more, and it hurts my soul.

Rather than get sad about it though, I got inspired to help. See, the common denominator in most of these 4G63 swap part-out’s was the wiring harness. If you have never dug into one before, it can be incredibly overwhelming, especially when you pull the electrical tape off. The once organized DSM harness becomes a spiderweb that has no beginning or end. WTFUXORS ensues.

So, in the interest of helping fellow 4G63 engine swap enthusiasts, I created a couple of wiring schematics.  One is a wiring diagram for a 1990 4G63 DSM.  The other is the wiring diagram for a 1991-94 4G63 DSM. Each one shows how the wiring harness needs to be setup for an engine swap.  Most importantly, it shows the MPI relay, which is the most challenging part to understand.

With that said, hopefully some people will find these diagrams beneficial, and if so, let me know.  If not, let me know what I can do to improve them.