BJ70 Cooling mystery solved! (1 Viewer)

Joined
Dec 16, 2004
Messages
1,115
Location
El Dorado Hills, CA
 
 
 
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 :flipoff2:

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 :princess:
 

tlcruiserman

SILVER Star
Joined
Jun 10, 2004
Messages
1,548
Location
San Diego, CA USA
 
Hey Brett,

Great news!!! So now that the temp problem is solved the big question is....Are you going to sell the BJ70 now? and if so, how much?

Cheers,

Michael
 
Joined
Jun 14, 2005
Messages
268
Location
Edmonton, AB
 
It sounds like Autometer might have a little problem on their hands with some QC. Your temp guage is one. Wayne also indicated he was having some problems in the guages he bought with missing parts. I hope this is just a bunch of Monday guages.

-kevin
 

crushers

post ho
Joined
Feb 10, 2004
Messages
22,180
Location
Tara Ontario
 
 
 
i bought another pyro the other day and the threads ont he back for tightenig down the gauge to the face were screwy... i am fast thinking i want to try a different brand...
 

wussyPup

just another ex-VI Cruiser
Joined
Apr 27, 2005
Messages
1,191
Location
Langford, British Columbia, Canada
 
dieselbigot said:
Yep...never did have a problem...imagine that. Seems like a bad dream you never wake up from...until today. I feel like I just won the lotto
Sorry, but I don't get it...

3 gauges recorded high temps:
- the original factory gauge
- the Autometer H20 replacement gauge
- the laser thermometer from the local shop
and one gauge recorded normal temp:
- laser thermometer from the dyno shop

Other than "wanting", why is the one laser thermometer from the dyno shop "correct" and the other three "wrong"?

I hope, for your sake, that the dyno shop thermometer is "correct", but I just couldn't follow the logic.

Thanks,
 

crushers

post ho
Joined
Feb 10, 2004
Messages
22,180
Location
Tara Ontario
 
 
 
now Brett, go buy that Snap on compression tester and glow plug hole adapter...
and test your compression again....
 
Joined
Sep 8, 2004
Messages
208
Location
Calgary, AB
 
Eric Winkworth said:
I bet, I think Isspro gauges are the only way to go, never wasting money on anything else ever again
I am on my 3rd Auto Meter oil pressure gauge in the last 6 months. They keep on getting internal leaks. I think I will stay away from Auto Meter in the future.
 
Joined
Sep 6, 2002
Messages
3,588
 
 
 
great, and that after I ordered 3 autometer gauges yesterday (pyro, water, boost) for a HJ60 to be turboed.
 
Joined
Sep 6, 2002
Messages
3,588
 
 
 
dieselbigot said:
For right now I just want to catch up on enjoying it...BUT, It's always for sale at $30k :)

hmmmmmmmmmmmh. should I trust that :D?

great the problem is solved-see you in pismo.

I suggest testing the 'bad' gauge in a regulated environment (accurate laboratory oven or so).
 
Joined
Mar 14, 2003
Messages
4,506
Location
Between Here and There
 
 
 
Interesting...
What was the head temp when the laser was 198 on the thermostat...

I'd be interested to know what your autometer reads in a pot of water on the stove with another known temp gauge. I'm with wusspup. I'd be skeptical of the logic and readings esp between 2 diferent lasers...

Glad you happy though.. I know what it feels like.
 
Joined
Dec 16, 2004
Messages
1,115
Location
El Dorado Hills, CA
 
 
 
wesintl said:
Interesting...
What was the head temp when the laser was 198 on the thermostat...

I'd be interested to know what your autometer reads in a pot of water on the stove with another known temp gauge. I'm with wusspup. I'd be skeptical of the logic and readings esp between 2 diferent lasers...

Glad you happy though.. I know what it feels like.
I actually ordered a Raytek laser and took it with me on some test runs. I'd run it up a hill and let the Autometer climb, then pull over and see what kind of readings I got on the laser. On average, the Autometer reads 20F hotter than the laser in almost every senario! I'm taking my readings from the probe on the T-stat housing and holding the laser as close to the probe as possible to tighten the range and ensure accuracy. I'm also taking readings from the top and bottom of the rad and those readings look great.

A few cliff notes here: First, back in the summer when I said the laser readings from the tech matched the Autometer, that was my recollection....in hindsight, I remember the tech standing way back when he was pointing his laser...I know now that this does NOT produce accurate readings at all. The farther you are from the object your'e pointing to, the wider the range you will get temps from. In other words, I don't think his readings (at the T-stat) were all that accurate and it just so happened that they matched (roughly) the Autometer. I also remember discussing with this guy how perplexing this problem was because he was getting 140F temps at the bottom of the rad. Bottom line, I had conviced myself (wrongly) that my problem was elsewhere and had eliminated in my mind the possibility that the Autometer was off.

Secondly, after doing some research I found that it's imparative that an electric temp gauge has an isolated ground if you want it to be accurate. Mine is NOT isolated as I just tied it in with my pyro and boost for simplicity at the time of install. The Autometer may in fact not be bad at all. I'm not happy with any of my 12V wiring and plan to re-do all of it this winter and will correct this ground issue then.

In the meantime, I feel very comfortable after multiple test runs using the laser to check my temps that I have no problems whatsoever :)
 

crushers

post ho
Joined
Feb 10, 2004
Messages
22,180
Location
Tara Ontario
 
 
 
when i install the aftermarket water gauges i run the ground back to the thermostate housing...
seems to work well for me...
glad to hear you are now a happy camper...
 
Joined
Jun 26, 2004
Messages
1,846
Location
east coast Canada
 
 
 
are you guys using elec. temp gauges....sounds like it when you are talking about grounds .
Use mechanical gauges and your readings will be far more accurate.

Daryl
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom