XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

A puzzle

Thread Tools
 
Search this Thread
 
  #1  
Old 06-22-2018, 07:33 PM
JigJag's Avatar
Veteran Member
Thread Starter
Join Date: Mar 2016
Location: North Carolina
Posts: 1,331
Received 580 Likes on 361 Posts
Default A puzzle

Anyone have any idea why this would occur?

Driving along in Light traffic, 100kph, 30C, Efan On. Needle is sitting right at the top of the N. Maybe a touch above. I thought it higher than it should be, not bad, just odd. For some reason I switched off the efan. Needle iimidiately dropped to just above the bottom of the N. Right where I’d expect it to be in these conditions.

How? Why?

Heres a pic for your trouble.


 
  #2  
Old 06-22-2018, 09:46 PM
VancouverXJ6's Avatar
Veteran Member
Join Date: Oct 2015
Location: Vancouver
Posts: 1,235
Received 537 Likes on 364 Posts
Default

My car's temp needle moves up or down a good 1/8th of an inch immediately if I turn anything on/off, like even the fan on medium. Far too quick to reflect an actual increase or decrease in temps. It could be nothing more then a voltage issue affecting the gauge needle way too much. Can you replicate this while idling? Like say..for example.. using jumpers to attach a dead battery to your running car and see if that draw causes the gauges to move around?
 
  #3  
Old 06-23-2018, 04:50 AM
Join Date: Feb 2010
Location: Adelaide Stralia
Posts: 27,306
Received 10,312 Likes on 6,822 Posts
Default

UMMMMM, Efan running backwards?????
 
  #4  
Old 06-23-2018, 06:33 AM
Daim's Avatar
Veteran Member
Join Date: May 2014
Location: Bremen, Germany
Posts: 5,906
Received 2,180 Likes on 1,583 Posts
Default

What about just the current draw possibly causing the instruments to lose some ground connection? Check your terminals. Might just be an electrical gremlin. Without a PROPER temperature gauge running independantly of the instrument cluster, it can be hard to justify if the temperature increase is just a gremlin or if it actually IS a problem...
 
  #5  
Old 06-23-2018, 01:01 PM
JigJag's Avatar
Veteran Member
Thread Starter
Join Date: Mar 2016
Location: North Carolina
Posts: 1,331
Received 580 Likes on 361 Posts
Default

Grant, nope! First thing I checked.

Certainly could be voltage change, but turning OFF a 17amp pull would make it rise if it were running low voltage right?

The drop I saw appeared to be a real reduction in temp. Not instantly. That was a poor word choice. It dropped over two seconds.

Im on other unrelated issues today. Four new injectors, a nos Vintage Performance GM module for the amp and a replacement vac advance unit. If it happens again after all that I’ll follow up with more details.
 
The following users liked this post:
Grant Francis (06-24-2018)
  #6  
Old 06-23-2018, 01:13 PM
Jagboi64's Avatar
Veteran Member
Join Date: Jan 2013
Location: Calgary
Posts: 4,758
Received 3,056 Likes on 2,031 Posts
Default

At 100 km/h you shouldn't need a fan, the fan can actually act to block some air going through the rad. Can you replicate the drive with the fan off and see what happens? Or try driving with the fan off and then switch it on and see if the temp increases?
 
  #7  
Old 06-24-2018, 07:29 AM
warrjon's Avatar
Veteran Member
Join Date: May 2010
Location: Vic Australia
Posts: 4,638
Received 2,576 Likes on 1,712 Posts
Default

I would see if you can replicate the issue,

Voltage variation will effect the gauges. A voltage drop should cause the gauge to read lower.
 
  #8  
Old 06-24-2018, 12:40 PM
EcbJag's Avatar
Senior Member
Join Date: Jun 2010
Location: Napa Ca, United States
Posts: 525
Received 193 Likes on 108 Posts
Default

+1 to Jagboi64. The fan isn't effective at speeds above 50-55 km/h. At 100 km/h the spinning electric fan might have actually been blocking airflow.
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
jbudnick
XK8 / XKR ( X100 )
6
09-20-2014 10:54 AM
jagular
XF and XFR ( X250 )
7
08-25-2013 05:18 PM
Wolfy
XJ XJ6 / XJ8 / XJR ( X350 & X358 )
8
12-10-2011 01:17 AM
Peter M
XK8 / XKR ( X100 )
2
09-17-2010 03:58 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


Quick Reply: A puzzle



All times are GMT -5. The time now is 08:17 PM.