Cylinder heads for dummies - Drifting forum

mazdachris · 24-09-2008, 13:29

A few months ago, my water pump failed and crapped all my coolant out. The engine overheated briefly before I realised and shut the engine down. I replaced the water pump and a few old water hoses and the car has been ok since, except it's losing coolant at a fairly steady rate (roughly every hundred miles or so I'm having to top it up). However there are no puddles under the car and no external signs of a coolant leak. it's also going through oil at a steady rate.

With this in mind, I'm rapidly coming to the conclusion that when it overheated, it blew part of the head gasket and now coolant is leaking through one of the cylinders.

Because of this, I've decided to replace my head gasket. I've done a few head gaskets and for the most part I'm fine with this, but I figure it'll be a good idea to give the head a bit of a freshen up while it's off the car. Now this is something I've not really done before and I want to make sure anything I do is done right.

So basically I'm after advice on what I should do to clean the head up. The gasket kit should include new valve stem seals and I figure grinding the valve seats would be a good idea as well. In addition, some kind of cleaning to remove carbon etc? But this is where I'm not completely sure how to proceed - what to clean and what to clean it with. I have some carb cleaner which I'm going to use on my inlet manifold which really blasts away carbon, and I've also got some swarfega which is good for cleaning up oil deposits etc.

Would it be an idea to give the head a bath overnight in the swarfega to clean the oilways etc, then spray down with carb cleaner the next day? The carb cleaner evaporates so shouldn't leave any residue.

I'm also wondering what tools I'll need for sorting out the valves. Obviously I'll need a suction cup stick doodad, and some valve paste (I hear that 1.5-2mm is a good amount of face to grind?) but I'll also need some kind of little spring compressor. Anything else?

Am I going to destroy my cylinder head through my bumbling ineptitude?

I would like to properly clean up my hydraulic tappets but I think this is a massive job that'd take about a week so I think I'll probably just leave them alone.

Any advice is greatly appreciated.

royal · 24-09-2008, 14:27

Are you sure you're not jumping to conclusions Chris? wouldn't the engine pressurise the cooling system, oil in the coolant, overheat, and mayo visible in the oil filler and all that jazz?

mazdachris · 24-09-2008, 14:47

Yeah, you'd think that. Bubbling coolant, mayo that kind of thing. No I've got magic disappearing coolant and oil. I've had all kind of leaks over the past year or so and I've addressed every one of them, to the point where I can't see anything leaking from anywhere (except my rear gearbox oil seal but obviously that's unrelated) so it seems that the only other place the oil and coolant can be going is through the engine itself. Especially since this seemed to start with the engine overheating.

To be honest, I've been offered a replacement cylinder head from a later car which should be in better condition than my current one and they flow a bit better anyway, so I figure I could buy this as an upgrade and if the issue is with my HG, then that'll sort that as well.

Though I'd still want to give it a proper freshen up before fitting.

topi · 24-09-2008, 15:17

Is the car smoking at all?

Depending how hot it got, there's a chance you may have warped the head. In which case it'll need a skim and a slightly thicker gasket (unless you want to raise the compression ratio - which is fair enough aswell haha). So it's worth getting the flatness of the face checked before you start working on it.

Other than that, you have the right idea.
Strip all the valves out (remember to keep them in ORDER. Get a load of plastic bags, and label up each set of valves,springs and retainers), de-coke the ports, chambers and valve faces (I use oven cleaner, though be carefull with this stuff as it's quite nasty), lap each valve in (unless the seat has been damaged, you wont need to use the course paste really), and put it all together.

It's easy enough aslong as you're organised to be fair. And it's worth getting a decent valve-spring compressor rather than struggling with crap stuff and probably damaging something.

Oh and try not to get any old gasket material in the oil ways when you clean the head down.

mazdachris · 24-09-2008, 16:44

If I get this newer head, as far as I know it's totally straight whcih eliminates the need for skimming. I was thinking about that myself. Increased compression couldn't hurt, really.

Sounds fairly good. Is there any use in sneaking it into the dishwasher if I strip it all down? I've done this with carbs before.

topi · 24-09-2008, 17:41

Cant do any harm, just make sure all the oilways are properly rinsed out after.

mazdachris · 24-09-2008, 17:59

Right well I've secured that replacement cylinder head. The only trouble is that it makes it a little more complicated swapping it over - I would just make tipex marks on the cam gears and timing belt to make sure it goes back where it should do. I guess I can still do that, I just need to put my cam gears onto the new head's camshafts?

I'm ok for the most part, but buggering about with valves is the thing which seems complicated and a bit scary. I'm sure I'll be ok though and the car should run well when it's finished.

I would think about having some work done on the ports etc but I don't have the money to get someone to do that unfortunately. Maybe I'll keep the old head and have some work done on that - big valves, solid lifters, nicely ported, wild cams, that kind of thing.

But NA tuning on an engine with a standard compression ration of 8.5:1 is always going to be a fairly pointless experience.

WideBoyS14 · 24-09-2008, 19:19

its easy, do it properly. strip the cams, lifters, and then the valves out. hot bath degrease. re-lap seats, new stems, rebuild. its soo easy that my girl was able to put all the valves and springs etc back in the head. i just used the spring compressor so she could use her lil fingers to put the keepers back.

as topi said, be organised and label everything!! it wont take you long, its jus the lapping which takes time!!

use a precision straight edge to check the flatness of the deck and head. i used a feeler gauge and a piece of glass.

mazdachris · 25-09-2008, 11:45

When it comes to replacing the stem seals is it just a case of removing the valve, then the old seal will pull out and the new one just presses into place?

Also, I'm sure I read somewhere that it's good practice to put the valves in loosely then check them for play to check the condition of the valve guides?

It all seems fairly straight forward really. At least with hydraulic tappets I don't need to worry abut shims and all that nonsense.

topi · 25-09-2008, 13:13

Yeah the seals are a simple off-on job. Sometimes they're a pain to get at, but I've never looked at the Mazda head.

But yeah check the valve stems, but they shouldn't be bad to be honest.

With the hydraulic tappets, when they're out.. squeeze them and get rid of all the old oil before you put them back.

24-09-2008, 13:29	#1 (permalink)
mazdachris Jam Hot Join Date: Oct 2005 Location: MK Posts: 2,206	Cylinder heads for dummies A few months ago, my water pump failed and crapped all my coolant out. The engine overheated briefly before I realised and shut the engine down. I replaced the water pump and a few old water hoses and the car has been ok since, except it's losing coolant at a fairly steady rate (roughly every hundred miles or so I'm having to top it up). However there are no puddles under the car and no external signs of a coolant leak. it's also going through oil at a steady rate. With this in mind, I'm rapidly coming to the conclusion that when it overheated, it blew part of the head gasket and now coolant is leaking through one of the cylinders. Because of this, I've decided to replace my head gasket. I've done a few head gaskets and for the most part I'm fine with this, but I figure it'll be a good idea to give the head a bit of a freshen up while it's off the car. Now this is something I've not really done before and I want to make sure anything I do is done right. So basically I'm after advice on what I should do to clean the head up. The gasket kit should include new valve stem seals and I figure grinding the valve seats would be a good idea as well. In addition, some kind of cleaning to remove carbon etc? But this is where I'm not completely sure how to proceed - what to clean and what to clean it with. I have some carb cleaner which I'm going to use on my inlet manifold which really blasts away carbon, and I've also got some swarfega which is good for cleaning up oil deposits etc. Would it be an idea to give the head a bath overnight in the swarfega to clean the oilways etc, then spray down with carb cleaner the next day? The carb cleaner evaporates so shouldn't leave any residue. I'm also wondering what tools I'll need for sorting out the valves. Obviously I'll need a suction cup stick doodad, and some valve paste (I hear that 1.5-2mm is a good amount of face to grind?) but I'll also need some kind of little spring compressor. Anything else? Am I going to destroy my cylinder head through my bumbling ineptitude? I would like to properly clean up my hydraulic tappets but I think this is a massive job that'd take about a week so I think I'll probably just leave them alone. Any advice is greatly appreciated.

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24-09-2008, 14:27	#2 (permalink)
royal S1- F.T break! Join Date: Nov 2005 Posts: 4,819	Are you sure you're not jumping to conclusions Chris? wouldn't the engine pressurise the cooling system, oil in the coolant, overheat, and mayo visible in the oil filler and all that jazz?

24-09-2008, 14:47	#3 (permalink)
mazdachris Jam Hot Join Date: Oct 2005 Location: MK Posts: 2,206	Yeah, you'd think that. Bubbling coolant, mayo that kind of thing. No I've got magic disappearing coolant and oil. I've had all kind of leaks over the past year or so and I've addressed every one of them, to the point where I can't see anything leaking from anywhere (except my rear gearbox oil seal but obviously that's unrelated) so it seems that the only other place the oil and coolant can be going is through the engine itself. Especially since this seemed to start with the engine overheating. To be honest, I've been offered a replacement cylinder head from a later car which should be in better condition than my current one and they flow a bit better anyway, so I figure I could buy this as an upgrade and if the issue is with my HG, then that'll sort that as well. Though I'd still want to give it a proper freshen up before fitting.

24-09-2008, 15:17	#4 (permalink)
topi KlutchKickKidz Join Date: May 2005 Location: Leicestershire/Derby Posts: 4,667	Is the car smoking at all? Depending how hot it got, there's a chance you may have warped the head. In which case it'll need a skim and a slightly thicker gasket (unless you want to raise the compression ratio - which is fair enough aswell haha). So it's worth getting the flatness of the face checked before you start working on it. Other than that, you have the right idea. Strip all the valves out (remember to keep them in ORDER. Get a load of plastic bags, and label up each set of valves,springs and retainers), de-coke the ports, chambers and valve faces (I use oven cleaner, though be carefull with this stuff as it's quite nasty), lap each valve in (unless the seat has been damaged, you wont need to use the course paste really), and put it all together. It's easy enough aslong as you're organised to be fair. And it's worth getting a decent valve-spring compressor rather than struggling with crap stuff and probably damaging something. Oh and try not to get any old gasket material in the oil ways when you clean the head down.

24-09-2008, 16:44	#5 (permalink)
mazdachris Jam Hot Join Date: Oct 2005 Location: MK Posts: 2,206	If I get this newer head, as far as I know it's totally straight whcih eliminates the need for skimming. I was thinking about that myself. Increased compression couldn't hurt, really. Sounds fairly good. Is there any use in sneaking it into the dishwasher if I strip it all down? I've done this with carbs before.

24-09-2008, 17:41	#6 (permalink)
topi KlutchKickKidz Join Date: May 2005 Location: Leicestershire/Derby Posts: 4,667	Cant do any harm, just make sure all the oilways are properly rinsed out after.

24-09-2008, 17:59	#7 (permalink)
mazdachris Jam Hot Join Date: Oct 2005 Location: MK Posts: 2,206	Right well I've secured that replacement cylinder head. The only trouble is that it makes it a little more complicated swapping it over - I would just make tipex marks on the cam gears and timing belt to make sure it goes back where it should do. I guess I can still do that, I just need to put my cam gears onto the new head's camshafts? I'm ok for the most part, but buggering about with valves is the thing which seems complicated and a bit scary. I'm sure I'll be ok though and the car should run well when it's finished. I would think about having some work done on the ports etc but I don't have the money to get someone to do that unfortunately. Maybe I'll keep the old head and have some work done on that - big valves, solid lifters, nicely ported, wild cams, that kind of thing. But NA tuning on an engine with a standard compression ration of 8.5:1 is always going to be a fairly pointless experience.

24-09-2008, 19:19	#8 (permalink)
WideBoyS14 JZS14FTW Join Date: Oct 2005 Location: cheam/sutton Posts: 478	its easy, do it properly. strip the cams, lifters, and then the valves out. hot bath degrease. re-lap seats, new stems, rebuild. its soo easy that my girl was able to put all the valves and springs etc back in the head. i just used the spring compressor so she could use her lil fingers to put the keepers back. as topi said, be organised and label everything!! it wont take you long, its jus the lapping which takes time!! use a precision straight edge to check the flatness of the deck and head. i used a feeler gauge and a piece of glass.

25-09-2008, 11:45	#9 (permalink)
mazdachris Jam Hot Join Date: Oct 2005 Location: MK Posts: 2,206	When it comes to replacing the stem seals is it just a case of removing the valve, then the old seal will pull out and the new one just presses into place? Also, I'm sure I read somewhere that it's good practice to put the valves in loosely then check them for play to check the condition of the valve guides? It all seems fairly straight forward really. At least with hydraulic tappets I don't need to worry abut shims and all that nonsense.

25-09-2008, 13:13	#10 (permalink)
topi KlutchKickKidz Join Date: May 2005 Location: Leicestershire/Derby Posts: 4,667	Yeah the seals are a simple off-on job. Sometimes they're a pain to get at, but I've never looked at the Mazda head. But yeah check the valve stems, but they shouldn't be bad to be honest. With the hydraulic tappets, when they're out.. squeeze them and get rid of all the old oil before you put them back.