What a topic for a first post.

In my 98 F150 4.6L, I have a small coolant leak coming from the lower passenger side firewall. I've been smelling pancake syrup for the last couple of days. There was no puddle or drip on the driveway so I don't think in its present form it's bad...but these issues never get better.

Anyway, I don't have any coolant leaks inside the cab, no steamy windows, no smell, nothing.

So, could this leak most likely be attributed to leaky O-ring/nylon spacer setup in the heater hose quick disconnects or a bad heater hose itself ?

Looking at the hoses next to the firewall, it looks tight. Does anyone know if these O-rings or hoses can be replaced without removing the intake? I don't think it's a leaky bypass hose as there is no coolant in the intake valley.

For future 1997-2003 heater related searches,
Ford Part #s
Heater core F65Z-18476AA
Heater supply hose XL3Z-18472AB
Heater return hose F65Z-18472BBB
5/8ths O-ring quick connects E69Z-18D434B

Thanks.

 

Yes, they both can be changed without removing the manifold.

 

Thanks.

I spent time checking it out this afternoon. It's not leaking from the heater return or supply hoses. The silver metal supply outlet and black plastic return fitting do not appear to be leaking either....but.....a search here has produced a possible culprit. It might be the heater bypass tube underneath the intake.

The leak reminds me of a compromised freeze plug on the backside of an engine. Looking at it, it looks like the coolant is coming from between the engine and trans/bellhousing. However, these motors aren't known for freeze plug corrosion and I flush/change my coolant every 18 months anyhow.

It's just a very slow leak...but I guess I'm going to have to order a set of intake gaskets and go on an expedition.

 

The supply tube is metal and runs from the back of the pump/top of the block below the intake.

The 98 bypass is only a 1/4 rubber line that plugs into the metal supply tube at the firewall behind the intake. From there it runs to a tree on the throttle body elbow. Other side of the tree, another rubber hose in connected. This runs to the front of the intake to the ECT sensor port. That's the bypass.

You said you have no coolant in the valley so it's either the feed or supply hose by the firewall.

They don't leak from the top, at least I never seen it - they leak at the connection behind the passenger side head. Both feed and return lines are problematic in this area.

Feed,Return and 1/4" bypass -

 

Man thanks a lot! I don't know if that rubber line is indeed my problem, but it sure would seem to fit the case. I saw all these pictures of metal bypass tubes underneath the intake and figured that's where I need to look. I didn't know about the connection at the pass. bank rear.

Like I said, there's no coolant puddling in the intake valley, but once parked, there is enough of a leak to produce a golfball sized wet spot.

Is replacing/repairing this connection possible without taking off the intake? I will remove the throttle body tomorrow and try to inspect the area you described.

Thanks again.

 

No problem - You don't have to take anything off. Connection is behind the passenger side head.

 

I just checked the metal feed tube (silver looks pressed in at the manifold) and didn't feel any spots or wetness. I twisted up a length of paper towel and wrapped it around its base and drove 20 minutes and didn't notice any orange coolant leaks. However, I could not get to the black plastic fitting (return line?) connection or the bypass tree connection to check it...guess they will have to wait till daylight.

Thanks again

 

Well I found the leak......

It's the !@#$%^'n head gasket!!!1! Why oh why couldn't it just be a heater hose connection or heck, I'd take a heater core install at this point.

It's a small leak, but it's there and now I must decide my 4.6L's fate. At 150,000 miles, it's been a great truck. I've kept up with the maintenance schedules and have really tried to ward off those high mileage demons.

Time to call up the mechanics and a dealer or two to get some estimates. I'm real tempted to use some of that $$$ head gasket in a bottle stuff, but I have my doubts. Even still, I'll know there's a weak link in the engine and could give out without warning.

Here's some pics.

 

...

 

What are you doing ?

 

He's leaving little raisins for you to pick up and eat. At least that's what I thought rabbits did.


Time for a PI swap, for the cost of a hg replacement at a shop

 

I don't care much for OLD raisins. This thread is from 2009.