5th Gen 4Runner Head Gasket - Page 2 - Toyota 4Runner Forum

Matt831 · 03-09-2023, 08:17 PM

Quote:

Originally Posted by Jeremy556

Keeps airflow from the fan pulling air through the a/c condenser and radiator. When the seal rots away, the fan pulls air through the radiator, but some from where that foam is, pulling in crap.

Sorry for the poor picture, but it's from several years ago before cell cameras were very good

Thank you. I had never known the exact reason after reading through a bunch of threads about it.

Rpede · 03-09-2023, 10:10 PM

Wow, this is why I love this forum and the people in it!! So many great response and I appreciate them all…gives me better insight. I know someone noted earlier that they wouldn’t replace the radiator if it had no sign of failure. How about the water pump with 130k? Nothing showing in the weeping hole. No abnormal bearing noise etc. I’m assuming it’s gotta be soon for it to start failing unless if the 4Runner water pumps have incredible longevity. I’ve been avoiding a preventive replacement for awhile because I’ve had not the best experiences with the Toyota dealer mechanics, some are incredible I’m sure just not in my area. I’m unable to find someone like an independent mechanic that knows a lot about 4Runners yet. I’m assuming that’s because they rarely break down and I think the 4Runner community on a whole does more of their own DIY maintenance compared to others but this is just an assumption. Changing the water pump DIY looks intimidating to say the least and I’ve done basic maintenance like replacing spark plugs, engine belt and brakes. I appreciate again all the responses and I’m amazed at how much one can learn on this forum.

Rpede · 03-09-2023, 10:15 PM

Quote:

Originally Posted by Jetboy

I think the best advice is above: Don't overheat it. I'm not actually sure what it would take because I could tow my 5500lb travel trailer over the biggest mountain passes in the southwest at 100* summer temps and the engine temp never moved more than plus or minus 1-3 degrees - but if you can find some way to overheat a 4Runner engine - don't do it. For perspective on the radiator - the 4Runner radiator has about 580 square inches of radiator cooling area. An F150 with the 3.5EB has about 510 square inches. They are very comparable in size. But the 3.5 EB will be generating a lot more heat. Probably twice as much. The 4R cooling system is very large relative to the cooling demand. A Tundra 5.7 radiator is around 700. A Powerstroke F250 is about 810. Toyota builds to a higher standard of reserve capacity.

I don't know that acidity is a big issue with modern extended life coolants. High quality carboxylate-based coolants like basically all new OEM coolants last a long time. They do not use silicate based protection and so they do not need to be refreshed with new fluid with a fresh level of silicate rust inhibitor additive every few years like legacy green silicate based antifreeze did in the past. Do they last forever? no. But 100k miles should be no problem. Especially in an engine like a 1GR that isn't going to have extreme heat. Few people ever flush or change coolant. And very few engines have problems resulting from that.

Incredible info. You must be a mechanic or an engineer. This is actually a very reassuring post.

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