Hello; There's what feels like a metal pipe inside the heater hose only a couple inches long. It has a clamp on the hose holding it in. What is this pipe thing? Is it better to leave it out? The heater hose has quick connects at the firewall, how do I take those apart? Is it best to ditch the quick connect and just clamp a new hose on? (1999 f150 5.4 PI auto 4r70w)

 

ah yes the flow restrictor

 

JDog1;7193659
Hello; There's what feels like a metal pipe inside the heater hose only a couple inches long. It has a clamp on the hose holding it in. What is this pipe thing? Is it better to leave it out?

< No, include it. A replacement will have one also. I rebuilt/spliced my hose, adding a new clamp to restrain this, and a brass elbow.

> The heater hose has quick connects at the firewall, how do I take those apart? Is it best to ditch the quick connect and just clamp a new hose on? (1999 f150 5.4 PI auto 4r70w)

< Ford "has a tool." Loooong right angle needle nose work. My pal has some (above) w an odd circular grab that seem prehistoric but must be ideal.

Ford erred. Flow through the heater was excessive. Cores eroded; Cabin noise w the *constant flow* core was [too] high. Their "fix?" Retrofit a hose w a restrictor.

A partial bypass is ok too, maybe w a gate valve. Omit this and see a core errode sooner than you'd like. Not fun to replace. I put a brass 90 near the eng front, which is the core's supply... w 3/4". Supposed to be 5/8", but it seemed too tight. Brass 90, then restrctor clamped in place, then 3/4 to ,5/8 plastic adaptor from OReilly's.

Hose from Dorman's did not like the semi-gentle radius, right out of the hot engine, at a high pressure point. Lost 2 sets. (Shop crossed 1st set. 2nd blew in a few months at spot of duress.) The additional 90 helps; the restrictor was put back into a similar location, re-clamped in place.

I may add a summer partial-adjustable bypass. Dad did for his '60 IH Scout. Idea is to make the core last longer. (He just wanted more cabin heat.) Another reason I am **** about flushes & coolant w 10th gens. Not a perfect design.

 

The restrictor will make the core last longer. I personally don't want my core bypassed with stagnant coolant sitting in there for 6 or 7 months.

 

I agree. I would not defeat the restrictor, nor would I fully bypass the core. For the summer I might reduce the flow to half. This would further reduce the core erosion that was discovered when no restrictor existed, while maintaining SOME flow, and making SOME heat available for one unseasonably cool morning. In MY area, cold almost doesn't happen. Bottom line is, *I* would put a valve in the bypass line. But not a high priority for me.

Old time cars controlled coolant flow to the heater core and some heater cores suffered from no summer flow, but many valves were cheap and still allowed minor flow.

 

There were a few RBV's that came with a vacuum actuated bypass valve. Maybe you could try one of those?

 

Those are great for things line Saturn AC - kill switches, to retain uphill power. I'll have to ponder that for a heater

 

I don't know the coolant flow path for the heater core on these engines, but on older engines I've worked on the heater loop for the coolant actually reduced cooling capacity of the system. Because the coolant was pulled from the back of the block before it passed through the engine, then returned to the water pump via a separate hose and inlet at the front cover. People that "bypassed" the heater core actually increased the chance of overheating, allowing lots of coolant that should have passed through the engine to bypass it instead. The water pump just pushed coolant through the hose and back to the pump inlet. The proper way for those older (Datsun) engines was to block the heater core ports if you weren't using the heater core.

It might be that Ford uses a restrictor for a similar reason. Something to consider.

 

[QUOTE=BareBonesXL;7195220]I don't know the coolant flow path for the heater core on these engines, but... /QUOTE]

On the 5.4, coolant for the heater core exits from the front top of the engine, straight up.
It enters a 5/8" hose the goes to a quick connect at the core,(on the left as we face working on it, I thiMk,) after passing through the restrictor, which is only a cute sliced block of plastic, shoved into the hose, near the front, and clamped in place. Exiting the heater core, from the right, a quick connect hose take the return to the rear of the engine.

(I found 5/8" hose tight, and used 3/4" hose at the front, to a brass 90, then 3/4 to 5/8" OReilley adaptor, with the restrictor somewhere in the mess, after the 90. My last hose blew right at the front, highest pressure and heat, right out of the engine, and a bend forced upon a straight hose.. Duh - )

 

I know for a fact that it was put in place on Mustangs and SHO's to protect the heater core. I actually have a few NOS brass restrictors (still in Ford Parts bags) for a Taurus that was part of a TSB, as I recall.




EDIT: For those interested, here are the TSB details in this thread. Although much of this pertains to checking for electrolysis issues, the quote below is what the issue was on SHO's and 302 Mustangs.

https://www.fullsizebronco.com/threa...ailure.408161/