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92 4 Runner - 3 ltr Over Heating


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a1handy
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May 27, 2015, 4:04 PM

Post #1 of 17 (1890 views)
  post locked   92 4 Runner - 3 ltr Over Heating  

Replaced head gaskets in Toyota 4 Runner 3 liter V6. Gaskets had blown. Had heads shaved and pressure tested. After heads replaced truck started fine but after idling for about 20 minutes took it on the road where it began to overheat. Took radiator to shop and was told it was working at about 40% capacity. We replaced with new radiator, thermostat and new cap. Same thing this time and began overheating only when on road. Replaced water temp sending unit. The top of the radiator stays cool until it begins to overheat. Bottom of radiator stays cool all of the time even while over heating. Does anyone have any idea of what may be going on. Could it be fan? Water pump, etc? What test might we try from this point forward? Many thanks


Hammer Time
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May 27, 2015, 4:55 PM

Post #2 of 17 (1885 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Did you ever determine what plugged up the radiator? Was the block full of more of the same which would just plug up the new radiator?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



a1handy
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May 27, 2015, 5:20 PM

Post #3 of 17 (1880 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

The tech at the radiator shop said it looked like rust and dirt along with stop leak. How can we determine if the block is circulating and if so what suggestions do you have to flush the block. We were planning on flushing water through the block by forcing water from the top radiator hose to the bottom of water pump.


Discretesignals
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May 28, 2015, 4:23 AM

Post #4 of 17 (1863 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

I know the 3vze had problems with head gaskets, but was it overheating before the head gasket job? When it is running hot does the heater work or are the heater hoses hot?





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(This post was edited by Discretesignals on May 28, 2015, 4:25 AM)


Tom Greenleaf
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May 28, 2015, 4:41 AM

Post #5 of 17 (1860 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Thoughts on this: If corroded inside engine (rust mud/flakes) it's almost fatal if bad enough for that block at least. There should be low plugs on either side of a "V" engine to drain all coolant not just one at a radiator. Common is you find those and when removed are full solid with crud if corroded. Most would "coat hangar" out and drain and can use harsher methods to clear out to a point.


Need to know what the history is about doing head gaskets too. Overheat or just leaks or corroded too? Usually if just a wild corrosion problem your heater would have given out or very poor performance then worse to nothing with use of sealer.


That too is a reason - if (many do) use the heater core as the by-pass for cooling which keeps all coolant the same temp INSIDE the engine till thermostat opens up still pumping coolant constantly. If it can't, away from thermostat can be boiling hot and at thermostat be cooler and confused again or damaged again with too hot one area and too cold another metals of an engine can't take that or for long.


BTW - This issue/problem comes mostly from use of plain water if this is the problem at all. More an issue with non automotive engine use such as if that block was also for other powered things, boats, pumps, generators and so on but think NOT this one. That market is well covered already lots older than this none known by Toyota to me.


So far with your notes on radiator alone by a radiator shop I take it, it doesn't sound so good without seriously flushing out if it will at all,


T



a1handy
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May 28, 2015, 1:45 PM

Post #6 of 17 (1845 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Thanks for your help. The heater works and produces hot air. I think the circulation problem may be within the block as well. It does seem to be some type of solid crud. The tech at the radiator shop said it looked like rust and mud. Please expand on the point you made about this being fatal. Can the engine be flushed as you say. What do you mean by more aggressive approach?
The reason for the gasket replacement was because the engine was steaming and passing water. The gasket was obviously blown when we removed it. Originally we used plain water but we added coolant and the same problem continued.


Discretesignals
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May 28, 2015, 8:21 PM

Post #7 of 17 (1838 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Was headgasket repair liquid added to the coolant system before you did the head job? If the heater is working, more than likely the water pump is doing something. Does running the heater with the blower on full blast when it is running hot cause the gauge temp to drop? Do you have good air flow through the radiator?
Depends on how cruddy this thing is and if the crud can be dislodged using just a water hose. There are coolant passages between the cylinder head and block that can plug up that a water hose will probably not be able to clear out. The worst case scenerio is the block will have to be flushed out using high pressure, but that will probably mean the engine will have to be dismantled and freeze plugs removed to do that.

Good that your running antifreeze in your coolant. Straight water will rust out the block and actually has a lower boiling point than a 50/50 mixture of water and antifreeze.





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(This post was edited by Discretesignals on May 28, 2015, 8:32 PM)


Tom Greenleaf
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May 28, 2015, 11:33 PM

Post #8 of 17 (1832 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Quote ">>What do you mean by more aggressive approach?<<"
Just that question: You would dunk the block in acid - not practical at all. The water jackets of a block do hold junk/crud at bottom out of reach of flushing and can pack up solid not exchanging heat there.


That's a long term use of plain water or perhaps a sealer that's too aggressive.


I'd pull at least one of those side plugs and dig out some of the debris anyway with this complaint to see if it's way too much and of what type - rust or something else.


If really this the heater really should have shown a problem or maybe the core has been replaced if you know at this age it might have?


May take some real analysis to know. Some cooling systems especially ones with use of dissimilar metals just electrically corrode debris, pocking seen on parts and usually those that do that clog radiators and heaters early or first? May also find fins of water pumps corroded badly adding to the search for why,


T



a1handy
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May 29, 2015, 3:50 AM

Post #9 of 17 (1823 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

I am going to run water through the block in an attempt to flush out any debris. How can I tell if it is circulating enough coolant? If the water runs freely without backing up is that sufficient? Should I have the motor running during this process? Should I try to add something to the water ( I notice posts that suggest you add detergent or CLR)? I understand the fan clutch could not be allowing the fan to turn fast enough so I may replace that as well.


Tom Greenleaf
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May 29, 2015, 7:07 AM

Post #10 of 17 (1817 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Why don't you pull those plugs out that I mentioned? That would be informative. CLR is an acid as said if this was some valuable restoration type project you would dunk whole bare block in much stronger acid. Not practical for this.
Back to now too late: When heads were off you could have run wire down water jackets for an idea better than now with it together. Flushing with real strong anything may work or not, may cause leaks in things like freeze plugs or who knows?


Fan clutches: Let's say most thermostatic (those have a temp sensitive spring on front toward radiator) detect heat from radiator and pull more air when warmer and almost freewheel when cooler except initial start up may pull hard for a few seconds.


If radiator and coolant if properly flowing thru it worked and clutch was warm you could watch it spin the fan, shut down engine while watching and fan would stop turning in a couple seconds. While running hot you can hear or feel the warm air blowing off of a good one. If radiator isn't getting heated coolant because it can't flow for any reason the clutch also wouldn't know to pull more air.


You could spray radiator with water when engine is fully warmed up and should have max cooling from the radiator then and temp stay steady at thermostat's temp. If it can't then flow is in question all thru the system, water jackets discussed and water pump's impellers may be incapable of adequate flow. Without looking right at it heater is a good clue also mentioned for clogging and flow issues.


When an liquid cooled engine can have hot spots unseen it can boil out of sight in a spot and not show air (vapor) of boiling elsewhere. That alone will warp heads and cause head gasket to fail or even crack parts if extreme.


IDK for sure with this problem. Might test with infrared touchless thermo what temps are where might just show a cold area of a hot engine or hotter area even before fully warmed up to open thermostat.
Trying for some pics of typical block drain plugs for coolant.............Not this engine specific......




Pic iffy if they show or expire above^^^^
These are chiefly ignored forever. There's little coolant motion down that low so junk collects there if any. Without corrosion protection they are about ALWAYS clogged up as said earlier you take wire or I said coat hanger to clear them then coolant comes out and more junk.
These could be hex heads, Allen headed, Torx maybe, square sometimes or other. Have to know where to look for them.


Forgive me but dealt with zillions of marine applications using automotive blocks. In those if "raw" water cooled it was annual maintenance to take those out and flush out junk every season never mind this being a 1992 NOT intended for "raw" water at all, marine would all be and still fail in about 10 seasons of use block with raw now salt (ocean) water would be replaced over it. Strange overheating was the first sign.


Whatever debris if extensive caught down there is in the cards not ever in my hands with a closed system using antifreeze all of which contain corrosion inhibitors. Short times of plain water shouldn't' really b a sudden problem?


In short if this was in front of me it would take some investigating all around to find where the source issue really is,


T



(This post was edited by Tom Greenleaf on May 29, 2015, 7:14 AM)


Hammer Time
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May 29, 2015, 7:12 AM

Post #11 of 17 (1814 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

I've done a couple that were real bad and ran about a quart of muriatic acid through the cooling system and then flushed it thoroughly. You have to be careful with that stuff though.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
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May 29, 2015, 7:25 AM

Post #12 of 17 (1812 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Doing battle with pics as usual HT. Muriatic Acid as you said dangerously strong as is Oxalic Acid. Just looked a CLR uses Sulfuric Acid. Dang vinegar (edible) is acid not strong enough.


Risk in this as some acids will eat right thru certain gaskets or items sealing coolant areas anywhere and cause harm. Doing this IMO is for extremes probably best left for the price is not object situations.


Marine auto block engines that crud up all I ever knew were just tossed for a new block or one already redone one if available and knew of none for that,


T



a1handy
User

May 30, 2015, 8:09 AM

Post #13 of 17 (1797 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Determined the water flow did not seem to be sufficient so removed water pump. The impellers on the pump seem to be facing the wrong way for a clockwise engine. Does anyone know of this engine being produced to run in a counterclockwise direction? Is there two different pumps available for this engine possibly. I have seen cars manufactured in us being different than those manufactured overseas. Thanks


Discretesignals
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May 30, 2015, 8:38 AM

Post #14 of 17 (1796 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

The water pump rotates counter clockwise. I don't think they make reverse direction pumps on those. It would also overheat idling and you probably wouldn't have any coolant flow if that were the case.

Should look like this:







Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


Tom Greenleaf
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May 30, 2015, 9:45 AM

Post #15 of 17 (1786 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

I didn't find a counter rotating pump for this and also checked a car with a 3.0 spins same way. Excellent thought as that is done on some engines.


Have you found those plugs yet? That would be so telling if this is a clog mess or not and be on with other ideas,


T



a1handy
User

May 30, 2015, 4:48 PM

Post #16 of 17 (1777 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

 
we purchased another pump and although it rotated in the same way the impellers on the old pump were significantly smaller and did not extend into the head at all like the new pump. We also noticed the timing was off by about one grove and fixed that as well. Not sure exactly what did the trick but when we started the engine, the water flow increase in the radiator was much better. Ran at idle for about 25 minutes and drove for another 30 with the gauge not going over 50% never near the red. I want to thank everyone who contributed, your help was invaluable. This is a great forum and I really appreciated the fact that everyone was patient and courteous and I did not feel insulted by my lack of knowledge as I do in some other forums. Great job guys


Discretesignals
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May 30, 2015, 5:17 PM

Post #17 of 17 (1776 views)
  post locked   Re: 92 4 Runner - 3 ltr Over Heating  

Very interesting. Glad to read you resolved your problem and thank you for following up. Smile Closed as solved. Can be reopened upon request by the OP.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.






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