Tip & How-To about Toyota Pickup

Straightening a 20-21-22R head

75-94 Toyota 20-21-22R Corona Celica Pickup, Four Runner.

These last a long time, there are lots of them still running, blowing head gaskets, warping heads, and we keep sending them off to be surfaced. One thing that is often missed is if the top surface is flat, if it isn't the cam will rock, if just a little the valve adjust will never be right and it will always make excessive valve train noise, if a lot, it will either break the cam, or seize it. Some machine shops that specialize in these engines have jigs to hold the head flat while the head is surfaced, most don't. We have found that if we take some soft 8th inch aluminum and make two inch wide pieces with notches or holes for the aligning pins, lay them on the block one front, one back, and blot the head down with the center six bolts, carefully, evenly until the head starts to flex, and leave it a while, a few hours, then tighten a little more, until it is just the other side of flat, keep the straight edge close, it needs to be within .004" or so. loosen it up and check, if it needs more, just tighten it down again, a little at a time and evenly among the six bolts, an easy way to tell if it's right is to have the cam in but no cam caps, then use the rocker assembly right on top, as you tighten feel the cam, when it stops rocking and spins free you are there, the cam journals are what we are most concerned about.

I have not had one fail, (yet), I would not do this on a turbo head as they are usually a different alloy and more subject to cracking.

Of course watch out for overheating that got hot enough to anneal the head, if so it will dent easily, a push type center punch works good, they have a consistent punch, do a few on it, then on a known good one, if they are larger, it has gotten soft, don't use it. Look also for electrolysis, if there is any visible in the coolant ports of the head, there will be more you can't see, don't use it if you or someone else is depending on it.

Hope this has helped

Sometimes fixing vs replacing makes the difference between making a job work, and it not being economically feasable.

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1 Answer

Toyota truck does it have to over heat to blow a head gasket

You don't need to overheat to blow a head gasket.

One other test you can do is remove the radiator cap and run the engine. There is likely to be lots of bubbles and perhaps even spouting of water out of the radiator if the head gasket has blown.

It certainly sounds like you have this issue.
By the way, you will use up all the coolant and damage the engine if you continue to run it with a blown gasket.

Nov 13, 2012 | 1992 Toyota Pickup

1 Answer

1987 toyota pickup with 22r keeps blowing head gasket

Your head bolts are stretched, when it got hot it weakened the metal in the bolts which means that the bolts cannot hold the needed tension on the head. Replace the bolts and you will stop blowing head gaskets. Also use Genuine Toyota head gasket, It will be a bit dearer but they are much better than aftermarket options.

Mar 07, 2012 | 1987 Toyota Pickup

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1994 toyota pickup blown head gasket. is that an easy fix? can i do it in my school autoshop and or driveway?

So the first question is ... is it really a blown head gasket? Could also be damaged head, block, etc and the timing chain can wear through it's housing and allow coolant into the oil. If it is a blown head gasket then why did it happen? Is the head warped, coolant passages corroded, or ?? Here's link to
a '93 manual to give you some idea what you're dealing with. http://personal.utulsa.edu/~nathan-buchanan/93fsm/ Can you replace the gasket in shop or driveway ... depends on what sort of
complications you run in to. You may want to have a valve job done while you're there, maybe
time to do the timing chain, etc. Give it a try.

Nov 29, 2010 | 1994 Toyota Pickup

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Blown head gasket will cause this so will a warped head, unproperly torqued bolts on the head, or even a crack in the block.

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Absolutely correct. Have cylinder head dye tested and checked for warpage before re-using. Do not run the engine any more than necessary ( into the garage or onto flatbed on it's way to shop) or you risk doing damage to engine bearings.

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