Overheat with strange assumptions

Tiny
TARSUSENDRI
  • MEMBER
  • 1996 VOLVO 960
  • 2.9L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 146,560 MILES
Hi there,

I gave this car to my brother to use since he needed a ride and was working on Dallas. After about eight months of usage, the car began to overheat. According to him, he made it home, and managed to replace the thermostat. Unfortunately, the car still overheated, enough so that the top radiator hose blew, which he ended up replacing too. I ended up having the car towed to my place so I can try and diagnose what is wrong with the engine, and found some interesting symptoms.

In order to see if it is the head gasket, I checked both the oil and coolant; the oil did not have the milk chocolate appearance, and the coolant did not look milky. The expansion tank cap also did not have the tell tale "mayonnaise*. After experimenting, I found some unusual symptoms. First off, the engine was actually maintaining a normal temperature as long as I keep the expansion tank cap off. The heater core was also turned on in order to try and bleed the system of air; the heater was blowing hot. When I put the expansion tank cap back on, the engine immediately began to overheat and the heater core started to blow cold (A/C was off). I am not sure if this is truly a head gasket problem, or if there is a clog in the system. The upper radiator hose does get very hot, and even hotter when I replace the expansion tank cap. I did order a head gasket leak tester, and am waiting for it to arrive. But is there any advice that I can follow to try and solve this problem? Could it be a clog on the radiator? Something simpler? Our could it really be the head gasket going?
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Saturday, February 11th, 2017 AT 9:21 AM

2 Replies

Tiny
CJ MEDEVAC
  • EXPERT
The radiator is a possibility. An infrared thermometer gun aimed at different levels/ spots of the radiator could indicate whether it is dropping the temps. Auto zone has one for about $30.00.

A radiator at Advance Auto Parts for $176.00 if yours is stopped up/ restricted. If need-be, this link might help.

http://www.2carpros.com/questions/2001-dodge-neon-milage-just-want-put-fliuds-their-locations

Are the cooling fans coming on when they should?

But first.

Not only can water get in the oil or oil in the water with a head gasket issue

But combustion gases can be 'pumped' into the water jacket or if you are losing coolant, it can be seeping into a cylinder.

You can do/have done a chemical test to your coolant (looking for signs of combustion gases). Other signs of this possibility are: Bubbling in the coolant/ pressure build up/ radiator cap not holding it's set pressure.

I grabbed this as an example

http://www.superstreetonline.com/how-to/engine/impp-1108-blown-head-gasket-diagnostic/

Water in a cylinder may show up as a spark plug being a lot cleaner than the rest.

Below is a picture of my 1946 Willys Jeep Head (1946 flat head 134 cu.in. cast iron head) I had water seeing into #4. See the discoloration of the combustion chamber? This problem also resulted in 'detonation' and a ruined piston and it's rings. Good news though, he is seventy years old and up and running again!

Performing a compression test might also reveal a problem cylinder. Before you tear into it.

Good luck/ keep us posted!

The Medic
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Saturday, February 11th, 2017 AT 10:14 AM
Tiny
CJ MEDEVAC
  • EXPERT
Pictures did not post. Second attempt below.

The Medic
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Saturday, February 11th, 2017 AT 10:17 AM

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