Murphy’s law is in full effect here… My daily vehicle began leaking coolant between the left side of the head and the block. Since the coolant was only leaking form the cylinder head and not being burnt in the engine I knew I could limp the car to work and back for a while longer just by topping up the coolant every day. I spent about three weeks topping up the coolant every 50Km to find out that I had lost a consistent 250mL of coolant. After weeks of these shenanigans my oil pressure light began to flicker at idle once the engine was up to full operating temp. I knew the Prelude was on it’s last leg at this point. The next day I drove it to school only to make it off the highway into Langley and have the oil pressure light come on and stay on… meaning very low oil pressure. I parked the Prelude and ordered a Honda head gasket and all other necessary parts to replace the top end.
My conclusion is that the oil light eventually came on because the cylinder head continued to warp and distort from driving it while leaking eventually leading to an oil passage between the block and the head springing a leak causing a drop in oil pressure.
The total job of removing the cylinder head, milling the head, setting the valve lash, and reinstalling totalled about 18 hours and $350 in parts. I disconnected and labelled all wiring, vacuum and coolant lines from the intake manifold and and head and removed both together with some helping hands. FWD cars sure don’t make it easy to access the area below the intake manifold towards the rear of the engine!
Upon removal the head gasket looked ok… I’ve seen worse…
The head was milled and reported to be cut down 0.004″ to make flat again. The service limit for cylinder head warpage on this H22a is 0.002″. This made me confident in my diagnosis.
After the tedious process of setting the valve lash on the 16 solid lifters in this DOHC VTEC head the head was cleaned and reinstalled with a new intake manifold and cylinder head gasket. Original head bolts were used at stock torque spec plus 4 ft-lbs.
I wrenched away until it was done and held my breath hoping I had not messed up the cam timing or camshaft torque as I turned the key to hear it crank for the first time. It sounded normal. I cranked the engine over for about 45 seconds with the ignition disabled so the oil and fuel pressure could build. I reinstalled the ignition relay and the Prelude fired up like it had never been taken apart!
I set the ignition timing with a timing light, check for leaks, then took it for a spin. I didn’t get a block away from the school before I suspected something was wrong. I pulled over and found two pinhole coolant leaks coming from secondary coolant hoses going to the IABV and FITV. I purchases some fresh coolant hose with new hose clamps at Lordco, cut new hose to length, clamped down firmly in place and enjoyed the new security found in replacing 18 year old coolant lines.
Since the head gasket replacement there have been zero engine problems. The engine no longer makes a clattering sound at cold idle because I corrected the valve lash and it pulls hard to red line. I couldn’t be happier. I’m back to my lovely daily from the late 90’s haha.
Overall this project reminded me of the correct methods and sequence or removing, labelling and storing parts that had to be taken off the engine. Although I had done a head gasket job a few times before, this was the first time doing significant work on a car that I loved and drove everyday. I took every precaution to not loose parts or bolts by working methodically and systematically from the official Honda service manual. This job has inspired confidence in my own work as well as confidence in helping students tackling this level of project.
Here’s a picture of the Prelude resting in it’s happy place, under a row of cherry blossom trees while not leaking anything!
Mr. McCormack