Builds Isuzu 4BD1T Lexus LX450 (Land Cruiser) Build

[Wheelingnoob]

Yep got the idea from your build.

Mine is sealed rad to spacer frame to rad support. So should not be getting much if any bleed off. If it hits the condenser its going through the rad.

Im out of town till Monday when I get back Ill get the rad I think. Cant see it being anything else. Wish there was a way to test other than dropping $400+ lol.


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[Wheelingnoob]

Spill timing?

This was done and set at factory spec at time of engine assembly. IIRC 13deg.


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[Dougal]

So last night on my drive from shop home (10min) it got hot 210f with in about 7 min so I turned the heater on full and the fan max. Cooled off enough to close the thermostat by the time I got home. So I continued driving under load with the heater on max i was able to maintain temp maybe a slight increase. As soon as I backed off and cruised it cooled off fast. Turn off the heater and the temp barely maintains it self under cruise and under load it quickly creeped up till I backed off at 210f. When I cruised after again with the heater off it ever so slowly cooled too about 200f and stayed there load would send it back to 210f again quite quickly. Turn o the heater again and would start cooling off.

I think my rad is shot, I had it checked when I had the inlet moved but I do not think they actually removed the tanks or flow tested it.

I have found a new replacement with a 4 core copper brass. Just need to bone up the $500 for it. Getting my rad recored to 4 core would cost me $490.....so will go new.

I think that is why my temps top to bottom are only 10f different at the best of times. A few times it been just as hot as the top even with the locked fan clutch. So the water that is getting through is not cooling.

Im away for a few days but plan to get the rad Monday if possible. I will also finish the shroud at the same time. At 2000rpm with the locked clutch I can feel air getting sucked through the grill so air flow I think is good.

As was said before at hwy speed I should not really need to fan to keep it cool. Right now even locked it does not keep it cool at hwy speeds.


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I'm not convinced you have a blocked radiator. If you did there would be very little flow and the tank temperatures would be very different. The inlet tank (presumably top) would be hot and the lower tank would be very cold.

Similar temps top to bottom suggest there is virtually no cooling but plenty of internal water flow.

 

[lostih]

Hey Jeremy-

Been out of the country for a week, but happy to come back and hear it's not a head gasket issue for you! Bummer about the radiator.

I think you have it narrowed down already, but here are some data points about mine that may be helpful to have here for future swappers.

1. I have a winch bumper on mine but it's low profile without lights...quite similar to the stock bumper. I do have the ac condensor in but not hooked up followed by the intercooler and fj60 radiator. I didn't do any sealing between them.

2. I am using the isuzu fan and clutch with no shroud. The radiator is moved back a couple inches but there is still quite a bit (maybe 4") between radiator and fan. This would lead me to believe that my fan is doing pretty much nothing but with the low blockage to flow from vehicle speed I seem to do fine.

3. I have not put the metal plate back on under the radiator.

4. I am water cooling my turbo by placing a t in each of the heater hoses before the heater switch. Essentially about 12" back from where the supply and return come out of the front of the engine.

5. I do have my rear heater hooked up for no good reason.

I have driven this way for 2-3k miles now all in summer months, but mainly on the freeway. I have done some off highway stuff but not tons. I have towed a 1500lb trailer over some 2000ft passes in 85f weather without the needle moving above the midpoint on the stock gauge.

I'm surprised that the winch and lights make that huge of a difference for you. It might not be worth it, but I'd be curious to see how it performs with a new radiator sans shroud. I guess I'm surprised that the winch and lights could make that much difference.

Clearly a shroud is the way to go. I can't decide on making one or just doing the ford contour electric fans. I really dislike fan shrouds for working on stuff...they always seem so difficult to remove.

 

[Wheelingnoob]

Yeah I'm at a loss.

With the locked fan I can suck a sheet of paper to the grill at idle so I do not think its an air flow issue.

The rad core is hot all the way a cross. No cold spots indicating a blocked or partially blocked rad.

I seem to have good water flow through the system or else I would have other issues I think?

I have got 100% of the air out of the system, the coolant level has not changed and I get no more air out of the bleeder at the high point.

Im lost now, I can pull the rad and have a flow test done on it again to tell me if its blocked at all. But if its not where do i look from there? Lack or slow water flow would result in a large temp difference from top to bottom of rad.

Can injection timing play a part in hot running? If so what? Advanced retarded? Fuel millage sucks right now but it is/was a fresh engine so Im not worried about that yet till its had time to break in.

Is there anything inside the engine that could cause this? Since Im getting no air or loss of coolant i do not think its a cracked head or head gasket. Those would have other symptoms as well.




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[IanB]

I can see how the lack of fan shroud could seem like no issue when the fan will suck paper to the grille at a stop, but when moving the air flow does some weird things, and if you end up with a high pressure area behind the rad, no air will flow through the rad, and you can't test that with the truck stopped. Before throwing more money and parts at this, I'd get a fan shroud in place and see if that has any effect, it's got to be cheaper than a new rad.

 

[Wheelingnoob]

Pulled the rad off and had it flow tested, kind of a stupid test really. Guy said it maybe partly blocked but I think he was fishing for billable work. I asked him how he could tell with a hose running through it if it was blocked or not. His reply was verging on asinine. So I am going to move forward with the assumption its not the rad.

Im working on the fan shroud now but I'm having a hard time believing with the shroud in place I will be in the clear. How can mine have so many issues. When lostih with the identical setup has no issues at all in hotter weather with no lower plate and no fan shroud and much more distance between the rad and fan. Let along towing up mountain passes. I mean fxxx I cant even drive along flat ground with out getting hot in 30* cooler temps no towing or even camping gear.


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[Dougal]

I can see how the lack of fan shroud could seem like no issue when the fan will suck paper to the grille at a stop, but when moving the air flow does some weird things, and if you end up with a high pressure area behind the rad, no air will flow through the rad, and you can't test that with the truck stopped. Before throwing more money and parts at this, I'd get a fan shroud in place and see if that has any effect, it's got to be cheaper than a new rad.

Absolutely. To me it's a waste of time and money doing anything but a shroud right now. There are extremely good reasons that all production vehicles and engines come with shrouded fans.

 

[Wheelingnoob]

Shroud is on, was not able to test it. Pulling the rad for the joke of a flow test was a waste of time. So it took me most the evening to get the shroud made.

Hope to test it tomorrow, really hope its the fix but am skeptical.


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[fabmec]

I've always found a flow test for radiators to be a waste of time unless the top tank is removed, just using a hose they will appear good on a larger core even with 80 to 90% of the tubes blocked. I've seen quite a few with the tubes looking fairly clean at the top and blocked about half way down, simple job to rod them out then put the tank back on. The only ones I had trouble with where the ones that someone had used a sealer like chemi-weld or bars leaks, nearly impossible to clean without splitting the tubes & tossing the radiator.

I think the fan shroud may help a bit but won't cure your heating problem now that you have done some more tests, the giveaway is that you said you can use your heater to cool the engine even with the fixed fan.

So just to go back over a few things, remembering that the heater core measures something like 8"x6"x1.5" thick,

1. You are using a used radiator.
2. You are not loading your engine (like towing).
3. You have good airflow (fixed fan, but shroud would help).
4. No air con heat added yet.
5. There is not much difference in temp between top & bottom rad tank.
6. Not much heat coming from your auto.
7. There is coolant flow.
8. You only have moderate ambient conditions.
9. You have said the engine temp rises fairly quick but hangs or takes a fair while to drop (unless you turn your heater on).
10. It seems that the heater core is working very well (also means your water pump is working), and under light loads it adds enough cooling capacity to keep your engine cool enough to function.

To me all this suggests only a small percentage of the heat from your coolant as it flows through the radiator tubes is being transferred to the air that is flowing over them. Sounds like you have a lot of blocked tubes.

Radiator may more than likely be the problem. If it was me I would take the top tank off & check it simply because it has not been done & there is a cooling system issue.

Graham

Just for anyone interested, picture of radiator flow test attached, this small alloy one was rodded out and flowed like new.

 

[Wheelingnoob]

Thats a great picture!

I have had plugged rads before and the dead giveaway was the hand test on the core. Mine is hot all the way across when checked no cold spots.

That's why this has got me so baffled. Testing tonight with the shroud in place to see if its any different.


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[wrongway around]

all great points fabmec. i too have found that a rad can feel the same all over ,had it checked ,it was all good. did a ton of other work on the car ,just about to scrap the thing cause of the heating issue.( i was putting a different head on a different block and it was suposed to be impossible) . put in a freinds rad and it was perrfect. so i brought the rad back to the shop had the top taken off and it was evenly half plus plugged with what looked like egg whites. flow tests are not perfect.

 

[fabmec]

Yes I've done the heat test thing too and it can be deceiving. I'll be interested to see what happens.

 

[doug720]

Well...I hope Jeremy's on a long road test after this fixed the heating issue!

Well...?

 

[kim]

I've got a 62 series rad that was good when I pulled it a few years ago, Jeremy. If you want it for testing, it's yours.

 

[ozwallaby]

Is it possible that your radiator is flowing TOO well and not having time to shed heat from the coolant....

 

[Wheelingnoob]

Thanks guys for the responses.

I got the shroud on the other day and tested last night and tonight. Its acting about the same as with out the shroud just a bit slower. I drove up to Greg's tonight and picked up his 62 4 core rad to try in mine and see if that is the issue. Thanks Kim for the offer I did not see the post till after I had gone up to borrow Greg's. I may interested in buying the one you have pending my test tough.

The locked fan with the shroud is impressive, I'm slightly worried its going to suck small children off the sidewalk at much over 2000rpm. I defiantly do not have an air flow issue at all now. I did make an interesting observation at Greg's tonight (10min of hwy driving to get there). After my drive up there I checked the top and bottom rad temps, we where comparing IR heat guns to make sure mine was accurate. My rad top tank was 185f, temporary gauge was showing 200f at Thermostat housing. The rad outlet was showing 125f.......so that kind of tells me two things one the water going through the rad is getting cooled. Second is I hope it tells your guys something that helps me sort this out. I would think it indicates slow water flow through the system or rad allowing the water in the core to get almost overcooled? its the only thing I can think of, possible bad water pump pumping water at a speed that keeps it cool under light load or short burst of high load. But then get it on the hwy with steady load its not circulating the water fast enough?

As usual lately, I'm at a loss.

 

[Dougal]

Is it possible that your radiator is flowing TOO well and not having time to shed heat from the coolant....

Nope. That's a myth. The faster you push water through the more heat is shed and the cooler the entire system runs.

Jeremy, now it sounds like you're down to radiator cores that are furry on the insides. You've got the low coolant flow and large temperature drop between the tanks that you should with enough air-flow.

 

[fabmec]

I think radiator is bad, restricted tubes inside. In some cases even a good working radiator with scale deposits on the walls of the tubes if let dry out the scale will peel and block or obscure water flow (and that was printed in more than one factory workshop manual from days gone by). Temps your observing would be what you would see with the thermostat near on shut ( low flow through radiator). As far as coolant flowing too fast to drop heat, the radiator will not have an issue with high flow rates, but certain engine designs will have will have issues if the thermostat is removed and the flow increases there.

You can test the water pump on the engine, bit rough but it works. With a cold engine you remove and plug your heater hose at the thermostat housing, then attach a piece of clear hose (about 10ft long) to the lower thermostat housing where the heater hose was connected, attach the other end of the clear hose to a broomstick, top up your water & leave the cap off the radiator. Then have someone start the engine and slowly increase engine speed with you holding the clear hose in the air with the broomstick. An operational thermostat must be fitted and the engine COLD. If the water pump is working coolant will lift up the tube sometimes 10 to 12 feet in the air at high revs.

 

[lostih]

I think (and hope) you'll solve it with the new radiator. Seems like it could be low flow causing all that as others have said...and the radiator seems like the most likely culprit at this point.