Is there a common coolant leak spot on passenger side rear of the motor?

[98EXPY 5-0]

Well I've got some kind of coolant leak somewhere. For a couple days I was smelling coolant occasionally with the heat on or off. Last night I could smell it on my way home and when I stopped at a closed gas station to use my credit card for gas, I shut the truck off. While pumping I saw steam coming from under the hood on the passenger side by the windshield. I popped the hood and got my flashlight. By then the steam had stopped. Nothing looked wet back by the firewall but I did see evidence of dripping on the ground directly under the firewall and maybe a little towards the rear. The passenger floor was dry. I tried to see where the heater core hoses went into the firewall, but I think what I was looking at was the air conditioner lines. I couldn't see anything wet or dripping, so I decided to drive the mile I still had to get home. I parked in front of my house and popped the hood and jumped out quick, hoping to catch some steam, but there wasn't any.

Other than the smell, it was running fine and my gauges never went out of their normal positions.

Is there a common leak point back there somewhere? I probably won't get a chance to look at it until this weekend, so it will just sit until then.

 

[hwy73]

Heater Core is first guess, which could run out the a/c drain onto the ground, but the trucks with rear heat/air were known to develop a leak near the "T" fitting in the heater hoses which would drip on cylinder #4 cop and take it out.

 

[JUST4FUN]

look above the number 4 spark plug there is a hose that has coolant going through it thatis your leak

 

[98EXPY 5-0]

#4 is rear passenger side right?

Is this hosed fixed by replacing or tightening a clamp or something?

Would this cause the coolant odor in the cab?

 

[Thermo]

98Expy, odds are, if you look on the firewall, you will see where the heater core hoses attach there. The connections are known to fail over time or from "abuse" during a plug change. I had this happen on my truck and I simply removed the hoses, cut the connectors off of the end and then slid the hose with a hose clamp back on to the nipple that was left. easy fix for me, but then, I had most of the top of the engine off at the time.

 

[98EXPY 5-0]

I found the two hoses with t-fittings (rear heat I presume). I tried squeezing the plastic wings that stick out to remove them, but it didn't come easy and I didn't want to break it if I was doing it wrong. How do these get removed.

I'm not even sure I could find the leak with them in my hand anyway. I guess I need to run it up to temp and look for the leak. I don't have any other way to pressurize the system to force fluid out of wherever the leak is.

Also, are these lines a dealer only part? I tried looking for them online without much luck, to see what it would cost to just replace both.

 

[98EXPY 5-0]

Well I rented the coolant pressure tester over the weekend. Only to realize that I don't have a radiator cap and there was not an adapter for the cap on the expansion canister. In fact, the kit might just be useless. I tried it on my wife's suburban and all it did was blow bubbles in the overflow jug.

Neither one of the T fittings is over top of my COPs. They are both between the battery and the valve cover. I didn't start the motor to let it warm up and spray again. I didn't feel comfortable spraying coolant on the street in front of the house.

I also had the guy at Autozone check and he only has the straight heater hoses, not the T-fitting ones for rear heat. He said that rear heat wasn't even an option given when putting my vehicle info in. So are these hoses DEALER ONLY?

Also, that little plastic clip doesn't seem like it would be enough to hold the pressure from the system.

 

[hwy73]

There is a tool that looks like an "L"-shaped, 2-prong fork that slides over those firewall fittings which releases the clips and provides a way to pull the hoses off. If you look on the beginning part of this video (2:40)
F150 Heater Core part 1 - YouTube
you will see the fellow do it. No "T" fittings, as he is working on an F-150. Then in part 3 when he is doing reassembly he does the rebuild kits for the fittings.

 

[98EXPY 5-0]

I guess I need to find one of these tools. I cut the old lines to get them out of the way. I can only get my hand on the left line on the firewall and it's not popping off. I can't even get my hand on the right side one until the left is off. I'm afraid to put too much pressure on it because I don't want to break the heater core hard line.

 

[Big White]

Well I rented the coolant pressure tester over the weekend. Only to realize that I don't have a radiator cap and there was not an adapter for the cap on the expansion canister. In fact, the kit might just be useless. I tried it on my wife's suburban and all it did was blow bubbles in the overflow jug.

Neither one of the T fittings is over top of my COPs. They are both between the battery and the valve cover. I didn't start the motor to let it warm up and spray again. I didn't feel comfortable spraying coolant on the street in front of the house.

I also had the guy at Autozone check and he only has the straight heater hoses, not the T-fitting ones for rear heat. He said that rear heat wasn't even an option given when putting my vehicle info in. So are these hoses DEALER ONLY?

Also, that little plastic clip doesn't seem like it would be enough to hold the pressure from the system.

I got the same tool from pep boys. Had to go back after getting home and get the "screw adapters" so that I could attach it to the de-gas tank (coolant reservoir). I thought I had a head gasket leak only to find out my cap was the leak. Win for me.

 

[Big White]

There is a tool that looks like an "L"-shaped, 2-prong fork that slides over those firewall fittings which releases the clips and provides a way to pull the hoses off. If you look on the beginning part of this video (2:40)
F150 Heater Core part 1 - YouTube
you will see the fellow do it. No "T" fittings, as he is working on an F-150. Then in part 3 when he is doing reassembly he does the rebuild kits for the fittings.

That guy is great. I subscribed to his you tube.

 

[wakeboarderNH]

My expy is doing the same thing... going to taclke it this Saturday. It looks like the hose just isn't on the heater core fitting all the way. So, should be easy enough.

 

[98EXPY 5-0]

I got most it plumbed last night after a trip back to Autozone because the kid gave me the wrong size hoses and fittings. The one part I'm not sure about is the connections on the firewall. I'd rather not use the quick connects again, but I don't think I can get my big hands in there to tighten two clamps. I can't even see the lines.

 

[rewarder]

Welcome to the club

 

[98EXPY 5-0]

Ok, I've been out of town for a wedding all weekend, so nothing more has gotten done. I also got my lines mixed up a bit. Does anyone have a diagram of the hose routing for a 4.6L with rear heat? I need to know does the hose that comes from the front of the block go to the left or right line on the firewall and to the front or rear line coming from the rear heater core?

 

[qcksnake]

Best bet is to pressurize the system and use an inspection mirror and light prior to pulling it apart. I have seen the rear of the plastic manifolds leak where they bolt down to the head, Gasket will look fine but they will leak. For this reason i will usually add RTV to the rear portion of the intake gaskets on the water port for plastic intakes. Oddly enough I only seen ths on the fel-pro gaskets. Never seen it on the ford intake gaskets.

 

[98EXPY 5-0]

After I got all the heater lines installed my truck ran like crap. I assumed that it was due to the fact that everytime I bumped the upper radiator hose while the lines were apart, coolant would pop out and land more or less on my coils. Not knowing which one was causing the issue, I decided to pull all the passenger side COPS and look for fluid and perhaps blow it out with compressed air. Well I didn't find any fluid, but I did find mud. I also found that the dielectric grease I put in the coil for #1 when the plug blew out had turned brown. I also learned that #3 and #4 coils didn't have any grease in them at all, but #2 did (still has the same plugs it did when I bought it.)

So I pulled each one, inspected the plug holes for fluid, wiped all the coils down and greased them up. I was only able to take a 15 minute ride, but it's already running better. Tonight I have some work to do that involves my EXPY, so hopefully I'll have good results and can call it "fixed" for now.

 

[mr49erguy]

I drove my 1998 Expy (5.4) from Northern Virginia to Utah a few weeks ago with the family and it ran like a champ. After arriving in Utah, I started smelling coolant in the cab, but did not give it much thought as I had no visible leak under the truck and the water temp was staying normal.

Wouldn't you know it, I left Utah to go back to work while my wife stayed behind for a couple of more weeks with her family 3 days before she was slated to drive the truck back home, she has a coolant leak under the truck, passenger side, just behind the firewall. Not only am I not in Utah, I'm not in the country (Germany). Luckily she has her family there and they have a big shop with tools and knowledge.

What they have decided to do since I am not there is to clamp the coolant lines just before they head into the firewall/cab. She has driven it around and left it running for 45 minutes with no visible leak or coolant smell. She is driving it up north tomorrow as a test drive to determine if it is road worthy and when she gets home I will inspect and replace the lines if necessary. Really hoping it's not the heater core itself as that could be a couple day job for a DYIer like myself.

My question is this temporary solution, keeping in mind that it is the dead of summer where the heater will not be used, a decent temporary solution?

Secondly, when I get to it myself, I wanted to know if anyone could tell me if they had any dampness in the passenger side footwell in the case of a heater core issue? I do not have any footwell dampness, so I'm hoping that this is a sign that the heater core is not the issue.

Thanks in advance from Germany.

BTW - While I was in Utah with my family, I decided to replace the driver side upper control arm and the passenger side tie rod end just because I had the wherewithal to do so and figured it would give my wife the best possible chance to get back in the Expy without any problems. They could have waited a bit longer, but the boots were not holding grease and I did not want to chance it. I was hoping that getting these items proactively taken care of would have warded off any travel truck demons, but I guess that did not work.

 

[IMINYOURCHAIR]

the heater core is in the same cavity as the ac evap and so it shares the condensate drain for the evaporator. any leak from that core is going to end up going out of this drain.

as for this old thread suddenly re awakening. I too have this right rear engine leak. I have found only some indication of where it comes from and believe it to be the freeze plug on the cyl head. I am not 100% yet as I have only just began to have time to investigate my recently developed leak. so far all I have is the trail of dirty leading from the bottom of it. this engine is otherwise clean/free of any leak trails elsewhere.

 

[AZ59apacheguy]

the heater core is in the same cavity as the ac evap and so it shares the condensate drain for the evaporator. any leak from that core is going to end up going out of this drain.

as for this old thread suddenly re awakening. I too have this right rear engine leak. I have found only some indication of where it comes from and believe it to be the freeze plug on the cyl head. I am not 100% yet as I have only just began to have time to investigate my recently developed leak. so far all I have is the trail of dirty leading from the bottom of it. this engine is otherwise clean/free of any leak trails elsewhere.

Mines leaking from the rear passenger side of the engine as well ( I started a thread on this in the Engine Section of this site ). It's seams to be leaking at the rear outer coner, between the head and engine block itself. It's not a lot and it only happens every couple of days, but it IS a coolant leak. Doesn't happen while I'm driving, doesn't happen when it's sitting the same day, it only ever happens the following morning. I have NO white smoke coming out of the exhaust, my enigne temps are normal and engine runs great. Mechanic says they did a pressure test on the cooling system and there was zero pressure drop over an hour. I have since bought a mechanics inspection camera with a long video scope. When it happens again I'm gonna take that camera and see if I can see what's going on.