Heater Hose Circuit Issue, Information Needed
Discussion
I have a TVR S1.5 with the 2.8L engine that I'm restoring. The small heater hose in front of the intake plenum cracked causing a loss of coolant. The hose goes from the water pump to what Ford calls a "spacer", which the auxiliary air device is bolted to. A hose leads from the bottom right of the spacer directly to the heater control valve, making it part of the heater circuit. While replacing the small section of hose I discovered that not only was the 90 degree elbow fitting corroded, it was completely blocked by corrosion, probably a good reason why the car's heater has never worked. The photo shows the fitting, next to the temporary silicone tape repair, and the upper part of the spacer. My question is: Does this spacer have any important function in the heater circuit? Or, is it just a conduit? I have to assume that if the upper fitting is blocked, the channel inside the spacer may also be blocked. I've tried to remove the upper elbow fitting but had no luck. It's locked in with 33 years of corrosion. If I'm unable to clear the channel or get a replacement, is there any reason I can't just bypass it and go directly from the water pump to the heater valve? 
It's been a couple of decades since I owned the V6 but as far as I remember the cooling system general design was fairly conventional:
Water pump takes an input from the bottom hose and pushes water into the block. The flow splits in the block and passes up through the heads and out to a water jacket in the inlet manifold. There is a stat housing at one end of the manifold. The main outlet from the stat housing hose to the top hose, swirl pot, radiator etc. The bypass outlet from the bottom of the stat housing goes to the top of the water pump. That's the main coolant circuit.
There is also a supply to the heater from the inlet manifold. I don't remember where it comes from on the V6. The heater supply goes through the bulkhead, through the matrix, back to the water pump. I think the heater control valve is usually on the supply side of the matrix but I could be wrong.
I don't know whether the V6 also has a throttle/carb heater. If it does, this would be tapped off from the heater supply and return hoses. If you have this in the circuit you'll want to get rid of it immediately.
Does that bear any resemblance to what you're seeing?
Water pump takes an input from the bottom hose and pushes water into the block. The flow splits in the block and passes up through the heads and out to a water jacket in the inlet manifold. There is a stat housing at one end of the manifold. The main outlet from the stat housing hose to the top hose, swirl pot, radiator etc. The bypass outlet from the bottom of the stat housing goes to the top of the water pump. That's the main coolant circuit.
There is also a supply to the heater from the inlet manifold. I don't remember where it comes from on the V6. The heater supply goes through the bulkhead, through the matrix, back to the water pump. I think the heater control valve is usually on the supply side of the matrix but I could be wrong.
I don't know whether the V6 also has a throttle/carb heater. If it does, this would be tapped off from the heater supply and return hoses. If you have this in the circuit you'll want to get rid of it immediately.
Does that bear any resemblance to what you're seeing?
Thank you for the reply. The 2.8l V6 with the Bosch K- Jetronic fuel injection system, to my knowledge, does not use a throttle or carburetor heater. The cooling system is basically what you've described. The short hose I'm concerned with comes from the top front of the water jacket and acts as either a supply or return for the heater circuit. It connects directly to the spacer plate. Fluid flows through the spacer and out the bottom through another fitting and goes directly to the heater control valve. The direction of flow is of less concern than why the Ford engineers are passing hot coolant through a passage milled or drilled into the spacer plate. It may have to do with the auxiliary air bypass device which is thermally activated and is bolted to the spacer. On the other hand, this device is only bolted to the spacer on an L bracket and doesn't make close physical contact in order to sense the heat in the heater circuit. There's also the fact that for most of the year the heater control valve is closed, meaning there's little or no fluid flow. A very curious arrangement. After further inspection, and the fact that no new spacers are available, it appears I may be able to remove and restore the one on the engine, assuming I can remove the fittings after 33 years. Or failing that, I could bypass the spacer altogether.
LoFlyer said:
question is: Does this spacer have any important function in the heater circuit? Or, is it just a conduit?
I suspect not so much the heater but more the A.A.Valve, this is controlled by an electric feed in proportion to warm up duration, however on semi warm/warm start the valve without any heat soak from the coolant will open and weaken the (WuR) adjusted mixture so until the AAV Closes again by the electric feed the mixture will be weak. In short it (spacer) appears to me a heat soak for the AAV.Very little experience with this mota but a little with K jet, my best guess anyway hth.
Thanks for the input concerning the AAV. Looks like I need to learn more about how the auxiliary air valve works. The engine idle goes unstable after it warms up, oscillating a hundred rpm or so around 900. Maybe the air valve is not operating correctly due to the lack of heat. Another mystery.
LoFlyer said:
Thanks for the input concerning the AAV. Looks like I need to learn more about how the auxiliary air valve works. The engine idle goes unstable after it warms up, oscillating a hundred rpm or so around 900. Maybe the air valve is not operating correctly due to the lack of heat. Another mystery.
Well that may be the answer ? It's 
Literally decades since I was involved so my recollection is hazy, I can't recall if the electric feed is timed out as the engine reaches operating temp thus relying on the heat soak to maintain closure of the AAV. If it is, this would explain the symptoms as it seems yours has no coolant flow. However if not, then it should be closed and the surging may be another fault !LoFlyer said:
There's also the fact that for most of the year the heater control valve is closed, meaning there's little or no fluid flow. A very curious arrangement.
I would expect this to be incorrect, I assume there'll be a bleed off to eliminate any influence by heater adjustment as the AAV requires to be controlled by engine temp. regardless of ambient temp.Edited by Maxdecel on Tuesday 5th October 11:58
Maxdecel said:
I assume there'll be a bleed off to eliminate any influence by heater adjustment as the AAV requires to be controlled by engine temp. regardless of ambient temp.
On the V8S there is an 'H' link pipe between the heater supply and return so that the circuit doesn't ever stall even if the heater is on cold. I'd expect to find similar on the V6.Okay, here's an update. I removed the spacer and, after some effort, the top elbow which was badly corroded and completely blocked. The spacer's L shaped internal passage was also completely blocked on the input (top) side. I've cleaned out the passage and am now awaiting the delivery of a brass replacement elbow. It seems this heater fitting is a rare bird and not an off the shelf item at auto parts stores. I left the lower 45 degree fitting in place because it was in reasonably good condition and the fact that 3/8" npt x 5/8" bead barb hose fittings are very difficult to find.
I also did some research on the Bosch auxiliary air valve and discovered that, indeed, it is electrically activated initially and relies on ambient temperature ( heat soaking) to keep it closed for a warm start. Because the TVR engine compartment is surrounded by GRP the ambient temperature drops more slowly than an all metal car. There is no bypass circuit I can find, unless the heater control valve is designed not to close completely. This is something I will check soon. In the meantime I removed and tested the AAV. The electric heater circuit appears to be intact with a resistance of about 40 ohms. Mechanically, I discovered that when hot the internal rotary valve did not close all the way, which means the engine would be running very rich even when at operating temperature, possibly the reason for the unstable idle. The interior of the valve was fouled with carbon, not unexpected since it's been in operation for 30+ years. I was unable to open the unit because it's riveted shut but was able to determine that the valve disk was still adjustable, therefore free to rotate, by shifting the calibration screw. After restoring the calibration screw position I blew out the interior of the valve assembly with brake cleaner followed by some WD-40 to displace any moisture, loosen any pivot bearing corrosion and leave behind some lubricant. Application of a Q-tip removed the fouling I could see. I then heated the valve with a heat gun and let it cool several times until the valve was again operational. It now closes completely when hot.
I'll let you know how if this solves the idle issue when things are back together. Thanks again for your assistance.
I also did some research on the Bosch auxiliary air valve and discovered that, indeed, it is electrically activated initially and relies on ambient temperature ( heat soaking) to keep it closed for a warm start. Because the TVR engine compartment is surrounded by GRP the ambient temperature drops more slowly than an all metal car. There is no bypass circuit I can find, unless the heater control valve is designed not to close completely. This is something I will check soon. In the meantime I removed and tested the AAV. The electric heater circuit appears to be intact with a resistance of about 40 ohms. Mechanically, I discovered that when hot the internal rotary valve did not close all the way, which means the engine would be running very rich even when at operating temperature, possibly the reason for the unstable idle. The interior of the valve was fouled with carbon, not unexpected since it's been in operation for 30+ years. I was unable to open the unit because it's riveted shut but was able to determine that the valve disk was still adjustable, therefore free to rotate, by shifting the calibration screw. After restoring the calibration screw position I blew out the interior of the valve assembly with brake cleaner followed by some WD-40 to displace any moisture, loosen any pivot bearing corrosion and leave behind some lubricant. Application of a Q-tip removed the fouling I could see. I then heated the valve with a heat gun and let it cool several times until the valve was again operational. It now closes completely when hot.
I'll let you know how if this solves the idle issue when things are back together. Thanks again for your assistance.
LoFlyer said:
Okay, here's an update.
I also did some research on the Bosch auxiliary air valve and discovered that, indeed, it is electrically activated initially and relies on ambient temperature ( heat soaking) to keep it closed for a warm start. Because the TVR engine compartment is surrounded by GRP the ambient temperature drops more slowly than an all metal car. There is no bypass circuit I can find, unless the heater control valve is designed not to close completely. This is something I will check soon. In the meantime I removed and tested the AAV. The electric heater circuit appears to be intact with a resistance of about 40 ohms. Mechanically, I discovered that when hot the internal rotary valve did not close all the way, which means the engine would be running very rich even when at operating temperature, possibly the reason for the unstable idle. The interior of the valve was fouled with carbon, not unexpected since it's been in operation for 30+ years. I was unable to open the unit because it's riveted shut but was able to determine that the valve disk was still adjustable, therefore free to rotate, by shifting the calibration screw. After restoring the calibration screw position I blew out the interior of the valve assembly with brake cleaner followed by some WD-40 to displace any moisture, loosen any pivot bearing corrosion and leave behind some lubricant. Application of a Q-tip removed the fouling I could see. I then heated the valve with a heat gun and let it cool several times until the valve was again operational. It now closes completely when hot.
I'll let you know how if this solves the idle issue when things are back together. Thanks again for your assistance.
Because the TVR engine compartment is surrounded by GRP the ambient temperature drops more slowly than an all metal car.I also did some research on the Bosch auxiliary air valve and discovered that, indeed, it is electrically activated initially and relies on ambient temperature ( heat soaking) to keep it closed for a warm start. Because the TVR engine compartment is surrounded by GRP the ambient temperature drops more slowly than an all metal car. There is no bypass circuit I can find, unless the heater control valve is designed not to close completely. This is something I will check soon. In the meantime I removed and tested the AAV. The electric heater circuit appears to be intact with a resistance of about 40 ohms. Mechanically, I discovered that when hot the internal rotary valve did not close all the way, which means the engine would be running very rich even when at operating temperature, possibly the reason for the unstable idle. The interior of the valve was fouled with carbon, not unexpected since it's been in operation for 30+ years. I was unable to open the unit because it's riveted shut but was able to determine that the valve disk was still adjustable, therefore free to rotate, by shifting the calibration screw. After restoring the calibration screw position I blew out the interior of the valve assembly with brake cleaner followed by some WD-40 to displace any moisture, loosen any pivot bearing corrosion and leave behind some lubricant. Application of a Q-tip removed the fouling I could see. I then heated the valve with a heat gun and let it cool several times until the valve was again operational. It now closes completely when hot.
I'll let you know how if this solves the idle issue when things are back together. Thanks again for your assistance.
Never even gave that a thought ! Seems to be OE on the Capri
Underlined That will weaken the mixture and likely result in the symptoms you have ie. an air leak.
Electrical supply for AAV & WuR comes from fuel pump so it is permanent as the engine runs, I looked.
Keep us posted, it's good to hear the outcome and refreshing to put ancient lessons to good use
According to the K-Jetronic manual the auxiliary air valve is misnamed. It actually provides a fuel-air mixture to the intake manifold via a bypass circuit thus enriching the idle mixture until the engine warms up. It also appears that the use of the heater circuit during the winter provides the AAV with additional ambient heat through its close proximity to the spacer This would keep its close-open cycle about the same after the engine is shut down as during the summer with the heater off since engine compartment would be cooler and lose heat faster in winter. Such an arrangement means consistent warm start performance independent of the season. Clever, those Bosch people.
Just rechecked the manual. You're right, I'm wrong. The AAV does provide additional air via a bypass circuit around the throttle plate which in combination with the cold start injector enriches the mixture during warm up. If it didn't close all the way it would lean the idle mixture. I've got to get more sleep.
LoFlyer said:
Just rechecked the manual. You're right, I'm wrong. The AAV does provide additional air via a bypass circuit around the throttle plate which in combination with the cold start injector enriches the mixture during warm up. If it didn't close all the way it would lean the idle mixture. I've got to get more sleep.
That's OK, took me a while to get my head round it Iirc? ! AAV Acts like fast idle as in the old days with carbs, also allows the enriched mixture more oxygen to enable the cold start process actuated by the WuR and the brief operation of the cold start injector.I guess the mixture will need adjustment after you've completed this ? Suspect it will have been richened to compensate for the excess air. Something to watch out for.
I've successfully rehabilitated the spacer, installed a new upper elbow fitting and replaced the straight hose with an L. It's all back together, including the now functional auxiliary air valve. And, to my amazement, the heater now works! Unfortunately the idle still went from stable to hunting after the engine warmed up. The WUR appeared to be working which left the idle mixture. Adjusting this proved to be more difficult than expected. The 3mm hex key would not engage the adjustment screw, as it was not completely vertical, possibly damaged by a previous owner. After multiple tries I ended up removing the mixture head which allowed the key to engage the screw. It took a number of adjustments, removing and replacing the head and restarting the engine, but eventually I was able to lean out the idle mixture and get a stable idle. Another small victory.
LoFlyer said:
.........including the now functional auxiliary air valve. And, to my amazement, the heater now works! Unfortunately the idle still went from stable to hunting after the engine warmed up. ........ The 3mm hex key would not engage the adjustment screw, as it was not completely vertical, possibly damaged by a previous owner. After multiple tries I ended up removing the mixture head which allowed the key to engage the screw. It took a number of adjustments, removing and replacing the head and restarting the engine, but eventually I was able to lean out the idle mixture and get a stable idle. Another small victory.
Two fixes for the price of one sounds good to me. I've never experienced a damaged adjuster, hard to imagine how it's possible? Maybe someone has been in the air flow sensor in an attempt to rectify the fault you've just fixed ?PitA removing dist. head to adjust it but seems like persistence paid off, good to hear the outcome, so often never posted.
Now I'm off to resolve the rattle at about 2200 rpm when accelerating. Looks like the engine mounts need to be replaced. I think the oil sump pan is hitting the anti-roll bar. That and replacing the steering rack boots. The front end also needs to be aligned. Does anyone know what the specifications for an S1 are or where I can find them? The car drifts to the left if I take my hands off the wheel while driving.
LoFlyer said:
Now I'm off to resolve the rattle at about 2200 rpm when accelerating. Looks like the engine mounts need to be replaced. I think the oil sump pan is hitting the anti-roll bar. That and replacing the steering rack boots. The front end also needs to be aligned. Does anyone know what the specifications for an S1 are or where I can find them? The car drifts to the left if I take my hands off the wheel while driving.
Suspension settings & alignment data are here:https://drive.google.com/file/d/0Bw2UHUb5GKJ6aF80e...
Useful Links - - > NEW Alternative Parts List pdf version) page 11/17
Sorry about the image, it's just a screenshot on my phone.
PS, Be sure that the ARB does not chafe through the sump pan. It has been known to happen.
Get those engine mounts changed ASAP.
You will need a 17mm flex head fine ratcheting combination spanner and the hands and wrists of a gibbon for this job
And a comprehensive Anglo-Saxon vocabulary.
Good luck.
Edited by glenrobbo on Friday 15th October 17:57
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