General engine questions/issues that aren't specific to the other categories
User avatar
By teal_dx
#38938 My civic would randomly get hot and I found there to be a grey sediment in my coolant, as well as a very fine oily substance floating on the surface. My head gasket may not have been blown, but there was definitely a leak from the combustion chamber into the coolant passage. Here's how to replace it:

The engine should be cool before starting.

Image
take note of the order of your plugs, then remove them.

Image
drain the coolant from the petcock

Image
Removing the radiator cap will help it drain faster. While it is draining, disconnect the o2 sensor and un-torque the header bolts (evenly in the correct order).

Image
Then on the intake side, un-torque all the bolts (evenly in the correct order). If you don't have a small enough wrench or ratchet to get the middle one through the hole in the middle, then you'll have to reach it from the bottom of the car.

Image
The coolant is through draining. Look at it in the right light and you can see the oily film on the surface. Yep that is not right.

Image
Next drain the oil. You could probably get by without doing this step, but now is a good time to change it.

Image
Disconnect the harness & coolant hoses from the head. (the towel was suffed into the dizzy hole to stop oil from dripping out)

Image
Image
After the oil has drained & you are putting the drain plug back in, unbolt the 2 bolts holding the header to the cat. Then finish removing the 9 header bolts on top and remove the header.

Image
Unbolt the valce cover bolts (evenly in the correct order) and remove the valve cover.

Image
unbolt the 2 10mm bolts holding the upper timing belt cover & remove it.

Image
Image
Check to be sure that the timing is at Top Dead Center (TDC) just like in the pic. This will make your life easier should the position of the cam or crank change while you have everything apart. Leave the transmission in neutral (or park) so that if someone accidentally spins one of the front wheels while it is on jackstands, the crank will not move.

Image
If it is not set at TDC, then turn the crank pulley by hand untill you reach TDC.

Image
Image
There is a small black plastic round cover. behind it is the timing belt tensioner bolt. You'll need to loosen it to get the timing belt off the cam gear.

Image
Loosen the timing belt tensioner bolt and then you will get the slack you need in the timing belt to slide it off.

Image
Next pull the intake manifold away from the head.

Image
Untorque the head bolts (or studs) in the procedure described in the manual. Then pull the head off.

Image
Have a clean area ready to set the head on.

Image
Clean the oil off of the surface and get your gasket scraper (or razorblade) to remove anything left of the old headgasket.

Image
Image
That's enough for today, it's like 15° out. If you plan on taking a break, be sure to cover everything up so no dirt gets inside.
Last edited by teal_dx on Wed Apr 09, 2008 5:10 pm, edited 2 times in total.
User avatar
By ohDirka
#38939 I zip tied the Timing belt to the pulley through the holes every time I did mine then pulled the belt light and tied it to the hood hinge. The timing was never off when I put it back on either :thumb:
User avatar
By teal_dx
#49770 Image

Image
here's how clean the block surface should be

Image
Next get your new, clean head gasket ready to put on.

Image
Optional is Copper Spray. I used it for extra insurance since this will be a boosted motor. It can help create a better seal.

Image
sprayed both sides.

Image
Then carefully put the head gasket on over the studs without touching the copper. Like that board game "Operation" (yeah I'm that old)

Image
Then put the head back on. Be sure the intake, timing belt and hoses are not going to be in the way.

Image
Applied ARP assembly lube to the studs. If you are using OEM headbolts, then never mind this and go ahead and put the bolts in now.

Image
Cleaned all of the nuts & washers of dirt & oil.

Image

Image

And torqued them to 70 ft/lb in the correct order. (if you are using oem bolts, check your manual for the specs)

Image
Now check to see that everything is still at TDC. If it is then tighten the belt tensioner. VERY IMPORTANT STEP!

Image
Bolt the Intake back on to the head.

Image
While doing so, I noticed this. No you don't need to remove the head to fix this. It is just a small ruber seal to keep dirt and oil (if your valve cover gasket leaks) from getting into the timing cover and ruining your timing belt.

Image
See the missing 10mm bolt between the belt & gear - loosen that and you'll gain enough play in the plastic piece to tuck the rubber seal back under.

Image
Now put the upper timing belt cover back on, then the valve cover.
tighten the bolts according to specs in the manual.

Image
Bolt on the Dizzy to the same place you marked it before you took it off. Then the plug wires.

Image
Don't forget the coolant hose & wiring under the dizzy when you're hooking all your hoses & harnesses back up.

Image
and hook up your vtec y0!

Put the header back on. Refill your radiator, oil, and then bleed the coolant system.

When using ARP Studs, remember that you have to re-torque them after 5-10 heat cycles. (can't remember which one it is right now.)
User avatar
By Gorveatt
#49775 This would have been handy if i decided to replace the headgasket myself, on my hatch... but i didn't... so someone else has to worry about it :lol:
User avatar
By BLACKS' COUPE
#49809 Great Write-Up Teal.. Just in time, cuz i was going to get the Head Gasket changed withing the next two weeks and now you are saving me 400 dollars that this mechanic wants to charge me. he said that you can damage alot of internal parts if you dont know what your doing but it looks like you are just using common sence and the manual.. lol :D
User avatar
By teal_dx
#49813 yep, that's all it takes :thumb:
Don't even try it w/o a manual. The correct torque & sequence is very important.

Also, you're not supposed to reuse the OEM head bolts for 92-95 motors because they are stretch bolts.
User avatar
By ohDirka
#49874 great write up :thumb: so you got the eg out in the nice weather? I heard it was like 70 out today
User avatar
By importcustomx
#110297 Did you take the head to a machine shop for plaining? ive always been told when you do that you should have the head machine'd before you put it back on. they just level the base part that sits on the top of the head gasket.

i was just curious if you did this.

Sorry im a long time lurker, mainley im on CRX community..but i saw this how to and wanted to ask.
User avatar
By importcustomx
#110339 okay awesome! well thank you sir


hell of a write up...well done!

if you dont mind im going to post a link to yours on crxcommunity.com