Turbo Dodge Forums banner
1 - 14 of 14 Posts

·
Registered
Joined
·
80 Posts
Discussion Starter · #1 ·
Hiya,

I have a 1990 2.5 turbo shadow that is overheating. The car was overheating when I got it and has a manual power switch hooked up to an aftermarket radiator fan.

I installed a new t-stat, new coolant, fixed a vacuum leak, and some other small things. After this the car started running at normal temps. I was able to drive the car for probably 40 minutes or so without any issues then parked it.

I was planning on driving the car to my storage spot yesterday, but it started overheating again immediately after trying to drive it. There are no coolant leaks and the level is exactly how I left it. The coolant is still its original color as well.

The PO thought the car had a head gasket leak for some reason, but there is no smoke coming out of the tailpipe at all, I am not losing coolant, and the oil on the dipstick is clean.

My initial plan is to run a combustion chamber leak test just to make sure there isn't a HG leak based on the POs comments to be perfectly safe. Then I'm not 100% sure what to do.

Should I be looking at water pump replacement?
 

·
Administrator
Joined
·
26,126 Posts
Is the car actually overheating or is the gauge just reading hot?

Is there any air in the system?
Did you use the proper drain and refill procedure?
Font Book Parallel Paper Paper product
Newspaper Font Parallel Newsprint Paper


Is the cooling fan cycling on at the correct temp?
Backprobe the CTS connector and read the voltage, the voltage translates to an exact temp.
Motor vehicle Automotive tire Automotive exterior Automotive design Coil
Handwriting Font Material property Parallel Rectangle


Another trick to help alleviate air and stop thermal shock on the headgasket when the thermostat opens is to drill a 1/16" hole in the thermostat flange and place the hole at the 12 o'clock position.
Courtesy Of Donavans Dodge Garage
Door Automotive tire Automotive lighting Rim Door handle
 
  • Like
Reactions: mh4ult

·
Registered
Joined
·
3,300 Posts
Also, it sounds like as good time to retorque the head bolts.

A few times I found them very loose and re torquing helped.

Thanks
Randy
 
  • Like
Reactions: mh4ult

·
Registered
Joined
·
80 Posts
Discussion Starter · #4 ·
Is the car actually overheating or is the gauge just reading hot?

Is there any air in the system?
Did you use the proper drain and refill procedure?

Is the cooling fan cycling on at the correct temp?
Backprobe the CTS connector and read the voltage, the voltage translates to an exact temp.

Another trick to help alleviate air and stop thermal shock on the headgasket when the thermostat opens is to drill a 1/16" hole in the thermostat flange and place the hole at the 12 o'clock position.
Courtesy Of Donavans Dodge Garage
I

Is there an easy way to test for air in the system? When I topped the radiator off I spent time allowing the system to self bleed with the cap off and also pumping/squeezing the upper rad hose.

I wondered if it was just reading hot because the car isn't boiling the coolant or anything. I wasn't sure how to translate voltage -> Temp so that chart is going to be a tremendous help. I'll try this. I also wasn't sure where the temp sensor location was . . . I cant' believe I didn't see it when poking around. I purchased one pre-emptively before I even took full possession of the car.

For the procedure - I can't really drain this at the cars current storage spot. I just topped the coolant off, made sure it started circulating, and filled the radiator/reservoir. I let it run with the cap off and spent some time allowing the system to bleed naturally and by squeezing the upper radiator hose here and there.

I'll keep the thermostat trick in mind as well.

Thanks!


Also, it sounds like as good time to retorque the head bolts.

A few times I found them very loose and re torquing helped.

Thanks
Randy
Good idea, thanks for the heads up (lol.) I'll get them torqued down once I get it moved to my primary storage/workspot :)
 

·
Registered
Joined
·
3,300 Posts
The retorque procedure is to start at 50 lbs and work up 10 lbs at a time.

Once 90 lbs is reached do the 4 corner bolts to 95lbs

You'll know while retorquing if any bolts move.

If they move you may have success!

Thanks
Randy
 
  • Like
Reactions: mh4ult

·
Registered
Joined
·
80 Posts
Discussion Starter · #6 ·
Thanks!

So I ran a combustion test three times, but can't get the tool to stop sucking in coolant. The steps I took:

1. Extract as much coolant as possible
2. Insert tool into rad cap area and make sure it has a good seal
3. Install bulb on top of tool and press bulb to generate suction
4. Start car and let it run

You can see bubbles moving through the test fluid as if its pulling air in, but the fluid remains its original blue color. After a while the tool starts sucking in coolant so I have to abort the test. I got tired of wasting the fluid so I just recorded a video so you can see what is happening. Since it pulls air for a while and the fluid changes color does this mean I likely DON'T have a head gasket leak and I'm really looking at something like a trans needing to be flushed?


I also tested the sensor voltage and it seems to be moving up/down appropriately. The voltage goes down in very small increments as temps rise and vice versa. The air that the radiator fan is pushing is so hot at times that I can't even have my hands in front of it. I've got a long video of this taking place, but its still uploading . . .my internet is terrible. Will post another reply once it finishes.
 

·
Administrator
Joined
·
26,126 Posts
In your sensor video, voltage got to 1.73 volts and the gauge was reading high, the question is...
Was this on the first or second stage of the CTS?
The CTS is a dual stage sensor, on a cold engine voltage will start high (approx. 2.80 volts =68 degrees, depending on ambient temp) and as the coolant temp increases voltage will drop to approx. 1.40 volts (117 degrees) then it will increase to approx.3.80 volts (127 degrees) and continue to drop again as the engine gets hotter, second stage voltage should reach approx. 2.10 (212 degrees) and the fan should cycle on and coolant temp should drop to approx. 192 degrees (2.50 volts) when the fan cycles off.

All of these numbers were live data taken from my car using a DVOM for sensor voltage and a scanner for actual coolant temp.

You also need to verify there is no air in the system by removing the coolant bleed plug in the head behind the thermostat.
Make sure the engine is cold, remove the bleed plug, fill the engine with coolant until the coolant sits at the top of the opening of the bleed hole and remains there, reinstall the plug and fill the radiator and overflow bottle.
If the bleed plug has not been removed in quite awhile it may be difficult to remove.(5/16" or 8mm hex socket, whichever fits tighter and a breaker bar)
Replacement plugs are available from Chrysler should you need one, they used them on certain vehicles up into the 2000's. (Mopar part #6034331)
Automotive lighting Automotive tire Rim Automotive wheel system Fashion accessory
 
  • Like
Reactions: mh4ult

·
Registered
Joined
·
80 Posts
Discussion Starter · #9 ·
Honestly I'm not sure what stage it was on. The car has a radiator fan wired directly to the battery with a toggle switch. I just left it on while checking. I will say that the temp gauge usually reads high, drops back down, then starts to gradually increase again - which I assume the point in which it drops down means it has gone to "stage 2?"

I didn't know the bleed plug was a thing! Funny enough - I found 2 bags of brand new OEM bleed plugs in the car yesterday. I didn't even know what they were for . . . lol. There is a good chance there is air in the system I suppose. When I first got the car it was bone dry. I spent a ton of time filling the radiator and trying to bleed all of the air out of the system. I'll try the bleed plug method next time I'm near the car and will report back :)
 

·
Administrator
Joined
·
26,126 Posts
I also feel that you need to repair the cooling fan circuit so it operates as it should.
My Son used a toggle switch on his 94 Sundance 3.0L cooling fan, he did this when he was bracket racing so he could turn the fan on after a pass, turn it on with the engine off to cool the engine and maintain a consistent temp.
He did not eliminate the factory wiring/setup, on the street the cooling fan cycled on/off normally he tapped into the ground side control of the radiator fan relay to accomplish this.
 
  • Like
Reactions: mh4ult

·
Registered
Joined
·
80 Posts
Discussion Starter · #12 ·
If it matters, the only codes I have set are 12 and 15

Yeah the previous owner set this up. I really hate the way he did it. The switch gets HOT I'm assuming due to incorrectly gauged wiring over a fairly long run. I had to do this on a LeBaron that wasn't getting signal to the fan relay . . .of course on the day of my emissions test. Wired it up in an auto parts store lot . . . lol. Mine is a much shorter run though and doesn't get hot at all. Its wired so that it powers on any time the ignition is on.

I don't have frequent access to a lot of my cars so I try to knock out what I can when I'm around them. Maybe I will swing by today and see if I can try a few more things.

My meter does have temperature probes. Will this help at all? Can I just push the probes into the radiator with the cap off to get more temp readings?
 

·
Administrator
Joined
·
26,126 Posts
Temp readings for the engine controller come from behind the thermostat, the radiator temp is not a good indicator of actual engine temp.
Motor vehicle Automotive tire Automotive exterior Automotive design Coil

Your switch is getting hot because it is controlling power rather than ground.
My Son had the same issue and kept burning through toggle/panel switches and I told him to do exactly what the engine controller does, control the ground side of the relay.
 
  • Like
Reactions: mh4ult

·
Registered
Joined
·
80 Posts
Discussion Starter · #14 ·
Good info about the switch controlling power. . . . I know not every circuit that is switched doesn't always control ground, but when I wire up something myself I usually use the ground since it seems to be the most common. Didn't know using power could have that side-effect :).

I didn't get a chance to work on the Shadow this past "weekend"- ended up working on a volvo and a 69 toronado instead . . . lol. The Toro runs now so that's at least progress on something.

I swung by the shadow this morning to grab some keys out of it and went ahead and pre-emptively sprayed that plug with penetrating oil - not sure if that will help or not, but can't hurt right? I'm probably dragging cars around this tuesday/wednesday between storage places so maybe I can squeeze some time in to pull that plug and verify no air in the system.

Thanks again for all of the help. I'll report back when possible.
 
1 - 14 of 14 Posts
Top