Engine/Transmission (1994 - 1998) Heater Core problems?

[Got Smoke?]

Just recently I've been having a lot of people mention they can smell anti-freeze around my truck while its running. If I run 'er pretty hard around town I can smell anit-freeze even without the heat on, however I usually smell it also when the heater first starts putting out heat.



Now I've skimmed some post's on this before and usually the passenger side floor is damp/wet when this is know to be leaking. Well I felt all over my pass. side floor tonight and none of it is noticeably damp/wet. Its not leaking onto the ground either because I park on really light colored asphalt at work and I would notice it at the end of the day.



I added 1/2 gal. of anti-freeze this morning before leaving for work with the truck being plugged in overnight, but that didn't fill up the radiator. After having set for a few hours tonight in my fiance's driveway I added another quart or so and it still wasn't full, but it was also cold so I quite adding.



Where would I begin to look for signs of trouble with this?

 

[Howard Durand]

What does the engine oil look like? Any change in level? There was something in the TDR recently concerning the engine oil heat exchanger leaking.

Can you smell it in the exhaust?

 

[ata]

97's seem to be the worst for the heater core leaking. Pull the carpet up and feel under it for water. Second, The 12 valve motors are notorious for the head gasket to leak coolant under the thermostat housing.

 

[Got Smoke?]

97's seem to be the worst for the heater core leaking. Pull the carpet up and feel under it for water. Second, The 12 valve motors are notorious for the head gasket to leak coolant under the thermostat housing.

I'll check that. I've already had the head o-ringed and installed a new set of bolts to 90Ft/Lbs + 90* torqued 3 times.



What does a heater core cost if that does happen to be the problem?

 

[JFaughn]

Get ahold of a pressure tester and pump it up and then look for leak , warm & cold eng. that should help to find the leak.

 

[Got Smoke?]

Get ahold of a pressure tester and pump it up and then look for leak , warm & cold eng. that should help to find the leak.

Went to a friends shop today and put a pressure tester on it. It repeatedly lost pressure (sometimes rapidly) and we could never find a source of a leak. Floor is dry as can be (under carpet too).



As if this wasn't enough I also lost heater vent controls today. Normally its just the hard plastic line @ the vaccum pump has slipped out of the rubbet L. Well its still zip tied in place and I still don't have anything other than defrost. #@$%! #@$%! #@$%! #@$%! Could heater core malfunction cause this?



PLEASE HELP! :{ :{ :{

 

[hsmith]

Engine oil in the vacuum supply can cause control problems, but not loss of coolant.

 

[Got Smoke?]

Engine oil in the vacuum supply can cause control problems, but not loss of coolant.

Hmm... . I found oil in the vacuum lines in the engine compartment after alreadying having blown & replaced a headgasket last year.



I've been wondering if the vacuum pump was on its way out with all of my 4x4 problems I've had this past year? And now this. :{

 

[JFaughn]

If your losing coolant and not finding any wet spots , check the exhaust tail pipe , could be that its leaking internaly.
And what about the dip stick any mosture , rust , discolored oil?

 

[hsmith]

Mine was repaired under warranty with a recall. Dealer installed a check valve at the vacuum pump. Did not apply to '97s though.

 

[Got Smoke?]

If your losing coolant and not finding any wet spots , check the exhaust tail pipe , could be that its leaking internaly.

And what about the dip stick any mosture , rust , discolored oil?

I have stacks. I did check the oil but its fine, regular BLACK oil barely under full "SAFE" reading



EDIT:

Is there a way to test the vacuum pump also? I already tested the coolant system like I stated above. Pumpe up to 17psi repeatedly, and repeatedly lost pressure... . sometimes very quickly down to 13-14psi. I still only have defrost, checked vacuum lines and couldn't find any holes in them?



I'm worried that not only has my heater core went out, but that my vacuum pump has as well.

 

[Hwyman]

Heater Core

On just having defrost try pulling the control knob off and see if is broke and not turning the shaft. Had the same thing happen on my 95 that's what it turned out to be.

 

[Got Smoke?]

On just having defrost try pulling the control knob off and see if is broke and not turning the shaft. Had the same thing happen on my 95 that's what it turned out to be.

I will look @ that in the AM, but I can feel each positive "click" with the turning of the knob.

 

[BigPapa]

Mark,



If you only have defrost, that generally means no vacuum. Defrost is the default position when vacuum is not present. With your 4WD problems and now this I'd lean toward you vacuum pump or lines. Good luck.



Scott

 

[hsmith]

Check the vacuum supply to cruise servo under the drivers side battery. May be broken at the servo.

 

[Got Smoke?]

Mark,



If you only have defrost, that generally means no vacuum. Defrost is the default position when vacuum is not present. With your 4WD problems and now this I'd lean toward you vacuum pump or lines. Good luck.



Scott

Yeah I knew that Scott, just forgot to mention it. Been down that road before. That little hard plastic line loves to slip out of that rubber boot on my trucks for some reason.



Truck has an appointment to be looked over in the morning. Going to have them check it over for heater core & vacuum pump failures. :{

 

[Got Smoke?]

Check the vacuum supply to cruise servo under the drivers side battery. May be broken at the servo.

This I did not know. CC has always taken 5-10 seconds to engage ever since I bough it also. I will most definately have them check that also in the morning as I will not be home to do so tonight & its below freezing outside right now. :{ :-laf

 

[Howard Durand]

You could by-pass the heater circuit by removing the heater hoses from the metal lines at the engine near the firewalll, connect the two metal lines back together with a short hose then run another pressure test on it. You should soon be able to tell which part of the system is leaking.

 

[Got Smoke?]

You could by-pass the heater circuit by removing the heater hoses from the metal lines at the engine near the firewalll, connect the two metal lines back together with a short hose then run another pressure test on it. You should soon be able to tell which part of the system is leaking.

Wish you had posted about 2 days ago Howard!



Truck already has an appointment with a local shop in the morning, so I'm not trying anything else. Owner has had several Dodge/Cummins for his farm and worked on plenty also so I'm sure he's seen a lot of things wrong with them.



Guess I will find out tomorrow, but thanks for the information.