Guys,
After 8 months of trying everything under the sun to solve my BJ70's cooling issue, the problem has finally been found...I'm pissed that it took this long to figure it out and that it's such a stupid thing, but happy the mystery is finally solved. Allow me to explain.
After going to Pismo last year I parked the 70 for some winter mods and maintenance. I did an axle rebuild, swapped out my 4.88's for 4.56's, swapped my 34 SSR's for 35 MTR's, changed all fluids, blah blah blah. The last and most important thing was swapping out my stock 3 core rad for a 4 core. Since I added the AC back in 2002, I had always had a bit of a heat issue that only every acted up on big climbs in really hot weather...naturally I attributed this to the lack of cooling ability of the 3 core. I had always put this off and just avoided driving it in the peak of summer.
So I completed all the work back in March, took it for it's maiden voyage and damned if it didn't run hotter than it every did...WTF?? So I started with all the obvious things...T-stat, fan, belts/hoses, temp sender etc...I decided that it must be the factory gauge that was giving me bad readings. No problem, so I drop in an Autometer H20 gauge...problem solved, right? NOT! On my first test run I was getting readings of 230F near Pollock Pines in 70F weather!. After discussing it with MUDer's, it was suggested that perhaps I had an air pocket as the 3B is notoriously hard to bleed the air out of. I took it to a local shop for a flush to make 100% sure all the air was out. When I picked it up I drove away and still got readings of 210-215….ARRGGHHH! I ran it back to the shop where a tech came out with a laser thermometer to check actual temps. The laser and my Autometer matched
So now I’m thinking cracked head…even though I’m not exhibiting any other signs like loss of coolant, white smoke etc…the 3B is famous for fissure cracks, so that might be it..right? Well after a good compression test (all even), leak-down test & coolant hydrocarbon test, that was not the culprit. So what’s friggin left?
I decided to have it dyno’d at a local diesel shop so we could see what was happening under load. We ran it up a 6% grade in 3rd gear, 3,000 RPM, 800F EGT’s and the temp gauge began to climb…180, 190, 200, 210. We pulled out the trusty laser thermometer and got a reading at the T-stat…188F!! Could this be it? Top of the rad, bottom of the rad, T-stat again…all under 190! We kept it on the dyno for another 10 minutes on 6% grade and I even shifted into 4th to really try and heat it up. The temp (gauge) climbed to almost 230F and the laser was still showing us 198F…perfectly normal and acceptable.
I’m off to buy a new gauge and plan to blow up the nearest Autometer factory
So am I happy?...you bet! See you all at Pismo with the 70!
PS...I have to mention one thing...Wayne told me so. he suggested months ago that this was problem was going to be somehting really stupid. Wayne, you were right
After 8 months of trying everything under the sun to solve my BJ70's cooling issue, the problem has finally been found...I'm pissed that it took this long to figure it out and that it's such a stupid thing, but happy the mystery is finally solved. Allow me to explain.
After going to Pismo last year I parked the 70 for some winter mods and maintenance. I did an axle rebuild, swapped out my 4.88's for 4.56's, swapped my 34 SSR's for 35 MTR's, changed all fluids, blah blah blah. The last and most important thing was swapping out my stock 3 core rad for a 4 core. Since I added the AC back in 2002, I had always had a bit of a heat issue that only every acted up on big climbs in really hot weather...naturally I attributed this to the lack of cooling ability of the 3 core. I had always put this off and just avoided driving it in the peak of summer.
So I completed all the work back in March, took it for it's maiden voyage and damned if it didn't run hotter than it every did...WTF?? So I started with all the obvious things...T-stat, fan, belts/hoses, temp sender etc...I decided that it must be the factory gauge that was giving me bad readings. No problem, so I drop in an Autometer H20 gauge...problem solved, right? NOT! On my first test run I was getting readings of 230F near Pollock Pines in 70F weather!. After discussing it with MUDer's, it was suggested that perhaps I had an air pocket as the 3B is notoriously hard to bleed the air out of. I took it to a local shop for a flush to make 100% sure all the air was out. When I picked it up I drove away and still got readings of 210-215….ARRGGHHH! I ran it back to the shop where a tech came out with a laser thermometer to check actual temps. The laser and my Autometer matched
So now I’m thinking cracked head…even though I’m not exhibiting any other signs like loss of coolant, white smoke etc…the 3B is famous for fissure cracks, so that might be it..right? Well after a good compression test (all even), leak-down test & coolant hydrocarbon test, that was not the culprit. So what’s friggin left?
I decided to have it dyno’d at a local diesel shop so we could see what was happening under load. We ran it up a 6% grade in 3rd gear, 3,000 RPM, 800F EGT’s and the temp gauge began to climb…180, 190, 200, 210. We pulled out the trusty laser thermometer and got a reading at the T-stat…188F!! Could this be it? Top of the rad, bottom of the rad, T-stat again…all under 190! We kept it on the dyno for another 10 minutes on 6% grade and I even shifted into 4th to really try and heat it up. The temp (gauge) climbed to almost 230F and the laser was still showing us 198F…perfectly normal and acceptable.
I’m off to buy a new gauge and plan to blow up the nearest Autometer factory
So am I happy?...you bet! See you all at Pismo with the 70!
PS...I have to mention one thing...Wayne told me so. he suggested months ago that this was problem was going to be somehting really stupid. Wayne, you were right