Dual Thermostats? Problems with my hose

gifu · 08-15-05, 11:42 AM

Having a strange problem that I have not encountered; and this being one of the few cruiser bb with some diesel experts....

I have a 1985 FJ60 with a Cummins 6A3.4t. I am running a stock radiator, cleaned out, new Napa-brand 13 lb cap. The engine has dual thermostats, relatively new.

The problem is the lower radiator hose keeps trying to blow off. No matter how tight I make the clamp. I assumed it was because the lower outlet of the radiator didn't have a "lip" on it. I had a shop put one on, and that solved the problem for a while. Then it did it again. I've never dealt with a dual thermostat system... seems overly complicated to me. Could a bad thermostat cause a hose to blow off?! What about a bad radiator cap? I would think that if the headgasket was blown (unlikely, it has not been overheated; no oil in the water, no water in the oil), it would first blow the cap (13 lbs)... but I'm not getting a large amount of fluid in the overfill. Maybe the new cap (again, Napa brand) is bad?

gifu · 08-15-05, 02:53 PM

OK... update. I am begining to suspect that the 15 lb radiator cap is too much. Stock is... 9? Opinions?

Landpimp · 08-15-05, 02:59 PM

yeah stock is .9 bar, which is I think 13lbs

silvercrusher · 08-15-05, 07:29 PM

Thats right 1 bar=1 atmoshere= 14.7 psi. I doubt an extra pound is what the problem is. You have a stock rad with a whole different system. You need the rad and cap for that motor; they design them that way for just such a reason. That engine likley requires a rad that has more capacity to cool and to take whatever that water pump is throwing at it.

.02

Good luck

08-15-05, 11:42 AM	#1
gifu IH8MUD Regular Join Date: Nov 2003 Posts: 251	Dual Thermostats? Problems with my hose Having a strange problem that I have not encountered; and this being one of the few cruiser bb with some diesel experts.... I have a 1985 FJ60 with a Cummins 6A3.4t. I am running a stock radiator, cleaned out, new Napa-brand 13 lb cap. The engine has dual thermostats, relatively new. The problem is the lower radiator hose keeps trying to blow off. No matter how tight I make the clamp. I assumed it was because the lower outlet of the radiator didn't have a "lip" on it. I had a shop put one on, and that solved the problem for a while. Then it did it again. I've never dealt with a dual thermostat system... seems overly complicated to me. Could a bad thermostat cause a hose to blow off?! What about a bad radiator cap? I would think that if the headgasket was blown (unlikely, it has not been overheated; no oil in the water, no water in the oil), it would first blow the cap (13 lbs)... but I'm not getting a large amount of fluid in the overfill. Maybe the new cap (again, Napa brand) is bad?

08-15-05, 07:29 PM	#4
silvercrusher IH8MUD Regular Join Date: Sep 2004 Location: vancouver island Posts: 345	Thats right 1 bar=1 atmoshere= 14.7 psi. I doubt an extra pound is what the problem is. You have a stock rad with a whole different system. You need the rad and cap for that motor; they design them that way for just such a reason. That engine likley requires a rad that has more capacity to cool and to take whatever that water pump is throwing at it. .02 Good luck __________________ "it'll only take a minute to fix" 85 BJ60 all stock so far 03 VW JETTA WAGON TDI

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08-15-05, 02:53 PM	#2
gifu IH8MUD Regular Join Date: Nov 2003 Posts: 251	OK... update. I am begining to suspect that the 15 lb radiator cap is too much. Stock is... 9? Opinions?

08-15-05, 02:59 PM	#3
Landpimp IH8MUD Lifer Join Date: Mar 2003 Location: Gig Harbor WA TLCA# 5506 Posts: 11,565	yeah stock is .9 bar, which is I think 13lbs