1987 4Runner
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RedRunner
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Looking for some advise on the overheating issue I have. It does great with normal driving but on going up the hills on I-70 and on steeper parts of trails, its climbs up to about 250. I have found two possible solutions for this, but both seem to be a bit pricey. The first is to replace the radiator with a larger aluminum one and the second one is to replace the coolant with Evans Waterless Coolant. Again, both of these seem to be a bit pricey.
Does anyone know of anything that I could try? I have dual electric fans on the radiator also which help but not completely.
Does anyone know of anything that I could try? I have dual electric fans on the radiator also which help but not completely.
J1000
Rising Sun Member
Water Wetter is usually good for a 10 degree drop, you can just add that to whatever coolant you have if it's fresh. Another free or nearly free thing that may help at higher speeds is to build some ducting around your radiator to force air through it and not allow air to find a way around the rad. Coroplast or ABS sheet is good stuff for that.
250 is probably higher than you should allow the temp to get. I'd pull over and let it cool around 220 personally, but that may be conservative.
I had issues climbing hills and doing trails in my cruiser after the 5.3 swap, but it would be fine on roads otherwise. I think it is finally solved with an aluminum radiator so I'd say to save up for a decent alum rad if you can.
Do you have a good fan shroud around the fans? Make sure there are no gaps between the rad and the shroud as well. Might also check the rad cap and make sure you have a high enough pressure cap for that engine. I'm assuming you should be around 15psi, so the cap should be something like 1.1 bar on the top. I wouldn't go too much higher than that if you are already there or you could blow your heater core.
I had issues climbing hills and doing trails in my cruiser after the 5.3 swap, but it would be fine on roads otherwise. I think it is finally solved with an aluminum radiator so I'd say to save up for a decent alum rad if you can.
Do you have a good fan shroud around the fans? Make sure there are no gaps between the rad and the shroud as well. Might also check the rad cap and make sure you have a high enough pressure cap for that engine. I'm assuming you should be around 15psi, so the cap should be something like 1.1 bar on the top. I wouldn't go too much higher than that if you are already there or you could blow your heater core.
Mechanical or electric fans? I'd try a new fan clutch if its mechanical.
RedRunner
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They're electric. I have a 16" single fan I can install also but was told the dual 8" was a better option.
rover67
Rising Sun Member
Its all about the airflow.... well a lot of it is.
If electric fans make sure there can be plenty of natural airflow, they tend to block flow at higher speeds especially if the shroud is close to the rad and kinda tight with smaller fan "holes". SOme shrouds have vents to allow air to push through if there is positive pressure in there. With no shroud you can also have issues since the fans don't pull air through the whole radiator but just a small part of it.
Also, me personally...... not great luck on water wetter but I use it every time I have a cooling problem lol. Either way running at 250 is damned hot and small stuff will likely not put a dent in it. I wouldn't even futz with fancy coolant. Also if it went to 250 and the cap didn't blow off I'd say that's probably sufficient. All you are doing with the cap is holding pressure to keep it from boiling at whatever operating (or above) temp you expect and 250 is hiiigh.
post a pic of the radiator/fan/shroud setup.
Also the radiator might be nasty inside?
If electric fans make sure there can be plenty of natural airflow, they tend to block flow at higher speeds especially if the shroud is close to the rad and kinda tight with smaller fan "holes". SOme shrouds have vents to allow air to push through if there is positive pressure in there. With no shroud you can also have issues since the fans don't pull air through the whole radiator but just a small part of it.
Also, me personally...... not great luck on water wetter but I use it every time I have a cooling problem lol. Either way running at 250 is damned hot and small stuff will likely not put a dent in it. I wouldn't even futz with fancy coolant. Also if it went to 250 and the cap didn't blow off I'd say that's probably sufficient. All you are doing with the cap is holding pressure to keep it from boiling at whatever operating (or above) temp you expect and 250 is hiiigh.
post a pic of the radiator/fan/shroud setup.
Also the radiator might be nasty inside?
rover67
Rising Sun Member
a good flush and fill might be a good start too. Don't go nuts on the ratio of coolant to water. DO what you need for freeze protection basically
RedRunner
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I will take some pictures tonight when i get home of the fan setup. I do not believe there is a shroud over he fans though.
RedRunner
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I was going to start with this and then drive up I-70 to see how it does with the fresh coolant. Would you recommend putting in the pre mix 50/50 blend or should I mix my own?
rover67
Rising Sun Member
either mix your own or the blend is fine but i personally am a stickler for using distilled water rather than tap water. Both options (premix and not) should be equivalent in terms of cooling. yo u'll just pay less for the latter but have more of an inconvenience.
RedRunner
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So I looked into the radiator more last night. From what I can tell, the radiator is not from an 87' 4runner or an 86' Mustang. I took some pictures but its hard to get a good idea of whats there from them. I have to assume that this setup has worked for while or the previous owner would have had issues also. The overflow reservoir is bone dry so that is leading me to believe that it might be low on coolant? I am going to try to drain, flush with distilled water and refill the system this weekend to see if it that makes any difference.
You may have lost a fair amount of coolant if you were hitting 250*, so not surprising your overflow is empty. Definitely do the flush and make sure to keep the reservoir topped off while it burps.
Looks like you already have an alum rad and is a decent size. Hard to tell how much open space you have in front of the fans to pull air, looks kinda cramped but may not be a problem. Also make sure if that is aluminum, that it is grounded to the battery somehow. Alum rads that aren't grounded have elecrolysis issues.
I have a brand new, still in the box, alum rad that I was going to use on my 40 with a 350 because the one on the truck sprung a leak but I got the leak fixed. That rad was working well for an old 350 so may be worth experimenting with for your application if you want to try it out.
edit - NM, doesn't look like the hose ports would match with the rad I have.
Looks like you already have an alum rad and is a decent size. Hard to tell how much open space you have in front of the fans to pull air, looks kinda cramped but may not be a problem. Also make sure if that is aluminum, that it is grounded to the battery somehow. Alum rads that aren't grounded have elecrolysis issues.
I have a brand new, still in the box, alum rad that I was going to use on my 40 with a 350 because the one on the truck sprung a leak but I got the leak fixed. That rad was working well for an old 350 so may be worth experimenting with for your application if you want to try it out.
edit - NM, doesn't look like the hose ports would match with the rad I have.
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SteveH
Hard Core 4+
That is a very thick radiator (compared to the slim, 2 row one you see on many new cars). It will take some effort to get air through that monster. There are some schools of thought where thinner is better, however I am no expert on this.
FJCDan
Rising Sun Member
My thoughts were the same with getting good air flow, with having the fan on the front your trying to push air through and being so thick you may only be forcing air through half of the radiator and not getting full effect. Unfortunately there is no room to put it behind because of engine being so close. You might try a double fan.
just a thought.
That's definitely a nice aftermarket aluminum radiator and should be plenty for that small block.
A couple of thoughts when I look at your setup:
1. As previously stated, pusher fan setups will block flow at higher speeds and actually counteract what you are trying to accomplish: airflow over the fins of the radiator. I think you could make different brackets and get the radiator further away from the engine so that you could put the fan/shroud on the engine side.
2. The shroud/fan setup is too small for that radiator. I don't know how much radiator is sticking out from the shroud on top, but that pick of the bottom shows 2" maybe outside of the shroud? Every bit helps and the shroud should go all the way to the edges of the radiator.
2. If you can create enough space in between the engine and radiator, I would definitely consider a mechanical fan inside of a better shroud. It looks like you only need about another 3-4". I see that you have an in-line coupler with a fill cap and that will allow you to make the top of the rad flush with the plane of the radiator support.
Good luck! I feel for you as overheating troubleshooting is frustrating!
A couple of thoughts when I look at your setup:
1. As previously stated, pusher fan setups will block flow at higher speeds and actually counteract what you are trying to accomplish: airflow over the fins of the radiator. I think you could make different brackets and get the radiator further away from the engine so that you could put the fan/shroud on the engine side.
2. The shroud/fan setup is too small for that radiator. I don't know how much radiator is sticking out from the shroud on top, but that pick of the bottom shows 2" maybe outside of the shroud? Every bit helps and the shroud should go all the way to the edges of the radiator.
2. If you can create enough space in between the engine and radiator, I would definitely consider a mechanical fan inside of a better shroud. It looks like you only need about another 3-4". I see that you have an in-line coupler with a fill cap and that will allow you to make the top of the rad flush with the plane of the radiator support.
Good luck! I feel for you as overheating troubleshooting is frustrating!
FJCDan
Rising Sun Member
My thoughts exactly.
Hood louvers! ... may help a little at dissipating the heat from the engine bay. To me it looks like a large portion of your rad is blocked by the fan shroud but you did mention that you have two 8 inchers in it so maybe I'm not seeing the second on the front.
I know the hood louvers and an electric fan worked well with my buds in line 6 in his Cherokee. But that wasn't a v8.
I know the hood louvers and an electric fan worked well with my buds in line 6 in his Cherokee. But that wasn't a v8.
That fan is 95% of your problem. It’s a single fan with more than 50% of the speed forced airflow blocked. A radiator should be able to cool on the hwy with essentially no fan at all! As others said, change it to a double at a minimum and ideally you have fans on the back side, not the front.
related question- take a photo of the clearance between the engine and the firewall. I’m curious if the engine can be moved back.
related question- take a photo of the clearance between the engine and the firewall. I’m curious if the engine can be moved back.
RedRunner
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Its hard to see in the picture but the fan is a dual fan, not a single. Unfortunately, I don't have room to move the engine back or install a mechanical fan on the front. I was trying to see if I could install the OEM fan and shroud for the 86 5.0 but I just don't have the room. The fan is currently controlled by a thermostat so I am going to try and change that to a standard on off switch. This way I can run them when I want to and not when they want to.