I'm replacing my engine in my 91 4runner because it has a rod knock. I picked up a 90 4 runner engine and was wondering what all I should replace.i was going to swap the timing belt and water pump out of my old engine because I just replace all that before the knock started.and I was gonna change the rear main seal.is there anything else I should change?
need some advice
- Thread starter jlallen
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Hey! I am wrapping up a rebuild and have been compiling a list of worthwhile things which might otherwise be overlooked, as a resource for others... good timing 
Are you planning to open up the engine more than you need to for the timing belt? If so you might as well replace the knock sensor pigtail, it's cheap and I'm told they fail often enough to be worth doing while you're in the area.
Valve cover gaskets and PCV valve are a PITA compared to some other engines, the better to do with the engine out. I relocated my PCV valve by using a 90* heater-hose elbow in the valve cover grommet, coupled with a length of rubber hose, to make the valve more accessible in the future.
I would check all of the sensors and hoses on the coolant manifold at the rear of the lower intake - they're difficult to reach with the engine in-car, and I might be tempted to just replace the coolant temperature sensor(the ECM sensor, not the gauge sender) because it's only $20-30 and hard to reach later.
I don't know what the year split is, but you may find the older engine has a different timing belt tensioner from your '91; you might need to buy a new belt anyway.
Good luck!
Are you planning to open up the engine more than you need to for the timing belt? If so you might as well replace the knock sensor pigtail, it's cheap and I'm told they fail often enough to be worth doing while you're in the area.
Valve cover gaskets and PCV valve are a PITA compared to some other engines, the better to do with the engine out. I relocated my PCV valve by using a 90* heater-hose elbow in the valve cover grommet, coupled with a length of rubber hose, to make the valve more accessible in the future.
I would check all of the sensors and hoses on the coolant manifold at the rear of the lower intake - they're difficult to reach with the engine in-car, and I might be tempted to just replace the coolant temperature sensor(the ECM sensor, not the gauge sender) because it's only $20-30 and hard to reach later.
I don't know what the year split is, but you may find the older engine has a different timing belt tensioner from your '91; you might need to buy a new belt anyway.
Good luck!
128keaton
New member
Hey! I am wrapping up a rebuild and have been compiling a list of worthwhile things which might otherwise be overlooked, as a resource for others... good timing
Are you planning to open up the engine more than you need to for the timing belt? If so you might as well replace the knock sensor pigtail, it's cheap and I'm told they fail often enough to be worth doing while you're in the area.
Valve cover gaskets and PCV valve are a PITA compared to some other engines, the better to do with the engine out. I relocated my PCV valve by using a 90* heater-hose elbow in the valve cover grommet, coupled with a length of rubber hose, to make the valve more accessible in the future.
I would check all of the sensors and hoses on the coolant manifold at the rear of the lower intake - they're difficult to reach with the engine in-car, and I might be tempted to just replace the coolant temperature sensor(the ECM sensor, not the gauge sender) because it's only $20-30 and hard to reach later.
I don't know what the year split is, but you may find the older engine has a different timing belt tensioner from your '91; you might need to buy a new belt anyway.
Good luck!
Pretty sure the 1992 year model was the switch. My 1993 actually has a 1991 head modified to use the newer tensioner. Not sure if you can go the other way though.
Coolant temp is a good idea.. Make sure you don't pinch any grounds. I've got a messed one somewhere screwing with cab stuff.
HanginInUtah
New member
Hey! I am wrapping up a rebuild and have been compiling a list of worthwhile things which might otherwise be overlooked, as a resource for others... good timing
Are you planning to open up the engine more than you need to for the timing belt? If so you might as well replace the knock sensor pigtail, it's cheap and I'm told they fail often enough to be worth doing while you're in the area.
Valve cover gaskets and PCV valve are a PITA compared to some other engines, the better to do with the engine out. I relocated my PCV valve by using a 90* heater-hose elbow in the valve cover grommet, coupled with a length of rubber hose, to make the valve more accessible in the future.
I would check all of the sensors and hoses on the coolant manifold at the rear of the lower intake - they're difficult to reach with the engine in-car, and I might be tempted to just replace the coolant temperature sensor(the ECM sensor, not the gauge sender) because it's only $20-30 and hard to reach later.
I don't know what the year split is, but you may find the older engine has a different timing belt tensioner from your '91; you might need to buy a new belt anyway.
Good luck!
1992 year was the last year for the spring tensioner. I learned about that when I did the timing belt on my '95 after doing the '92 a year or so ago.
I would add your front main seal and your oil pan, which will make it a little easier to do your rear main. And, don't forget your oil cooler... seals and coolant hoses.
I also replaced ALL of my heater hoses when I did my recent engine work, and the fan belts. Check your fan clutch, and consider it and your radiator if they're not awesome. No reason to lose your engine right after the work if they're not top-notch. Oh, and the thermostat. That's a no-brainer.
