Head Gasket Replacement

[sdoan]

Ok... so the Plot Thickens...

1. The exhaust valve on cylinder 1 has a small piece missing out of it. (I believe this would cause a compresion check on this cylinder to come up short)
2. Secondly I noticed that inside one of the Cylinder 4, their is actually a small groove that starts about halfway down, and continues out of site below the piston. (I believe that this small groove may also be causing some pressure loss.)

I've been looking online and I have found some Toyota Cylinder heads for around 250... It's a bit more then I want to spend but if I could get another year or two out of the car I would be happy. What are your thoughts?

If the groove is deep I might know what it is. I had a big Healey that was designed with wrist pins (connect piston to connecting rod) held in the small end of the connecting rod with a pinch bolt. There were no clips to hold the wrist pin from floating in the piston. The pinch bolt came loose and the pin slid to one side until it ran into the cylinder wall where it left 2 parallel vertical grooves. The Tercel engine has a similar design - if the wrist pin slips it could leave a groove. If the groove is vertical and 90 degrees to the line of the engine block it may be a slipped pin. If you see 2 parallel grooves about 1/2" apart it almost certainly is the wrist pin. If the pin has slipped it might make more sense to find a donor 3A or 4A engine.

If the groove is not a wrist pin and not deep enough to catch your fingernail on the cheap way would be to buy the $4 exhaust valves and the head gasket kit (with gasket and valve seals). Put it together and run it. It might be nearly as cheap to just replace the whole engine with a used engine. I found a usable 4A on craig's list for $300.

If you replace the head gasket ...I've had good luck with Felpro gaskets and bad luck with cheaper Chinese gaskets (failed right away). Stick with good quality gaskets and retorque the head bolts hot like the FSM says and you should be OK.

[keith]

If you have more that 150k miles on this engine, chances are that when you put it back together, its going to burn a lot of oil. The renewed compression will unseat the rings. I've never tried this but next time I'm confronted with a head gasket change and valve reseating, I will scuff up the cylinder walls with either very fine sand paper or red scotch bright. The rings should reseat quickly, that my theory anyway.

[MontanaMike]

Ok, so I just checked in the FSM about putting the Cylinder Head back on and could not find anything about re-torquing "hot" It talks about it on page EM-31. If you do want to install them "hot," how is that done?

[Neu]

Ok, so I just checked in the FSM about putting the Cylinder Head back on and could not find anything about re-torquing "hot" It talks about it on page EM-31. If you do want to install them "hot," how is that done?

with a propane torth.

Lol, just kidding. I had to make a joke tonight though.

[Petros]

$250 is too much for a used head. You can get one at a self service yard for about $40 (like a Pull-A-Part), but it could be just as worn as your head. You should be able repair your head for far less. The damage exhaust valve is not uncommon, I would replace all of the exhaust valves, they are cheap, and once one goes bad the others many not be far behind. If you run your ignition timing at about 9 or 10 deg BTDC instead of the factory 5 it will give more power, economy and not burn your exhaust valves. The factory timing was to reduce emissions, but it causes the exhaust gases to be hotter since the fuel has not finished burning when the exhaust valve opens.

Have the intakes valves reground and have the head resurfaced, and replace the valve seals. All of this should cost less than about $100 I think, and it would be far better than a used head.

I would not worry about the line in the cylinder walls unless it is badly gouged, that just comes from wear and perhaps it was run with low oil once. It seems very unlikely redoing the valves will cause any issues with the rings. To do anything about it you have to pull the engine, than pull the pistons and rods, replace the rings and hone the cylinders. Then you would have almost a rebuilt engine, so you might as well replace the bearings and low end seals while you are at it. A lot more work and expense, and probably not necessary. Consider it ran with this line in the cylinder wall for many thousands of miles without harm.

You can clean the top of the engine block real good with 800 grit sand paper and real flat surface like a steel plate or smooth tile as a sanding block. Clean both the head surface and the top of the block real good with brake parts cleaner, including the bolts hole. Use a small bottle brush in the bolt holes, blow them out with compressed air and solvent if you have it. Make sure you clean the bolts real good too, and then use light grease on the head bolt threads and on the washers when you install first them or it will not torque accurately.

I have always retorqued my head after running it for the first few hundred miles, but the new gaskets are not supposed to require retorquing. So you will not see it in the manuel anymore. I have done it both ways with out issues. If you do retorque it you have to turn it backwards just enough to break it free, and then tighten to specified torque in the normal sequence.

Good luck.

[MontanaMike]

Ok everyone... first off, thanks for all the input. I am currently waiting on the new valves to show up in the mail. Scheduled for delivery tomorrow. But I wanted to thank everyone for their awesome input. Without you guys I would not have had the courage to undertake this whole project! I've got everything all polished up and ready to go... just waiting for the new parts to arrive, pop'em in and (cross your fingers) it will work! I'll be sure to keep you all posted. Thanks!

[Neu]

pics please if you could. They're always appreciated on the forums.

[MontanaMike]

I started a new topic with the most current problems...