5A-F head issue

TC · Post by TC » Sat Dec 01, 2007 12:38 pm

I recently bought an 83 tercel 4wd that had a used Japanese 5A-F engine put in it. There is a problem with a stuck or bent valve that won't close and I am going to have to rebuild the head, but it seems very hard to get parts for these Japanese 5A-F engines. Does anyone know if other heads are compatible, such as the 4A or 7A? Or does anyone know where to get head gaskets, parts and specs for the Japanese 5A? Any help would be greatly appreciated.

ESI-RStarion · Post by **ESI-RStarion** » Sat Dec 01, 2007 3:21 pm

Well the 7afe is an injected head, So that one's out.

83toybeater · Post by **83toybeater** » Sun Dec 02, 2007 9:40 am

id just put a 3a head on it. they are probly the same i have one off if you need pics or anything

Typrus · Post by **Typrus** » Sun Dec 02, 2007 11:22 am

I'm pretty sure all the "A" heads are interchangeable.

I'd vote you try to find an entire 4AF head. NOT 4AFE. The E means fuel injected. Or just look for a 4AGE head and do a side-draft carb swap

A 4AF head would do you well.
The 3 or 4AC heads would drop your performance a noticeable amount. If thats not a big deal, go for it!

GTSSportCoupe · Post by **GTSSportCoupe** » Fri Dec 07, 2007 11:06 am

The 5AF is a dohc engine, and I agree with the above, the 4AF head is probably the same. Make sure to stick with the carb'ed variant (not 4AFE as Typrus said). 3AC and 4AC are sohc engines, so valve reliefs in the 5AF pistons won't match the heads.

Post by **Petros** » Fri Dec 07, 2007 8:16 pm

what do you mean by stuck? If someone messed up the valve timing on the belt then it could have bent which will not allow it to close. This is not unusual, or if the engine swallowed a washer or a bolt or something, it could also bend it. Either way the head has to come off.

You could take a good valve out of it and either go to the dealership or a good parts store and see if you could match it. Even the FSM I think had dimension of the valve stem, head, length, etc. Likely they did not make special valves for just the engines sold in Japan, some 80-90 percent of their production is sold in North America.

Jts · Post by **Jts** » Fri Dec 07, 2007 9:11 pm

Have you taken off the valve cover and looked to see if the valve isn't moving when you spin the crank? I highly doubt that the engine is an interference engine, as almost all toyota engines of that time were not.

TC · Post by TC » Sun Dec 09, 2007 2:05 am

The previous owner of the car said that he couldn't get the valve into spec. i.e. it had too big of a gap, and stayed open throughout he compression stroke, he said he even swapped the valve spacers around to give the stuck valve the biggest stack and still had no luck. So I am in the process of pulling the head to see whats up, hopefully it is simple and the local machine shop can fix it up, if not I will have to order a rebuilt head.

keith · Post by **keith** » Sun Dec 09, 2007 8:47 am

If the valve is open during the compression stroke and the gap is there also, then the valve is either bent or has excessive carbon build up on the stem. You will only need a new valve.

Typrus · Post by **Typrus** » Mon Dec 10, 2007 12:33 pm

At most you might need a new guide as well. But thats not a big issue.
I agree. Pull the "bad" valve and a known good one, compare them. Roll them on a table and watch the stem. You'll see a bend if its there. Or you'll see the carbon. If it is carbon buildup, a good overnight soak in some SeaFoam or BG44k will loosen her up. If you're brave, you could boil some Simple Green (Super Concentrate!!) and pop in the valve. That'll loosen the goop up. Just make sure to have good ventilation. Simple Green may be environmentaklly friendly, but let me tell you what... It'll sure make your skin tingle and lungs burn!
I did that to clean up an old power steering pump I had that needs to be re-sealed. Cleaned it like a charm.

If its bent, take the known good one to a NAPA or CarQuest and see if they have some Toyota valves sitting around. You know, the 4AF valves could very well be the same.