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760 Coolant, lots, pax interior side only

W

whalepirot

New member
Joined
Jan 21, 2017
Location
kalifornika
Finally got the car to be awesome, thanks to y'all. Prior owner had new red block installed, possibly due to O'heat. The heater control valve is plastic aftermarket; a big clue, plus the comments here about their rrequent failures.

Since I fixed it properly, there has been a varying, no trace wet spots foound, of coolant loss. I've not seen a driving or other use pattern that caused them, but at times it would go for well over a week, then need a fair amount of coolant added after one day; this in a very mild climate w/o heat needed.

Yesterday, on a long drive on a hot day, I found a LOT of coolant in the passenger footwell. I was able to refill the partially cooled-off engine with more than a gallon, as it idled. Beiung 45 miles from home, I thought it may not be proper fill technique but it lasted 40 miles, when I noticed the formerly mid-range temp gauge, suddenly near full hot. Pulled to the freeway side, let it cool some, then had her sip some water, again at idle. It got home, but the rear footwell was found to have wet carpet as well.

I couldn't find any threads relating to dry driver side/wet passenger side, but learned what a PITA it is to change the heater core. Having only owned the car for about a year, I know it was initially Arkansas owned, then move to Palm Desert, then to SoCal coastal; the heater was not used much, I bet. I could probably live with the heater bypassed, save the winter days when defrost is needed, but prefer a proper fix. That could be a diagnosis path.

The bypass outlet canot leak coolant into the interior, being entirely ooutside the firewall There may be occasional drips on the ground, vicinity of the firewall; not seen much at all. The two heater hoses through-wall on the diver's side, where one would expect driver-side coolant wetness. Are the feed tubes to the heater long with the core on the pax side?

Thanks in advance for reading this longish post any your considered input.
 
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Sounds like a heater core to me. They really arent that bad to do. Just mark everything (wires, bolts, vacuum lines) as you take it apart. It may be a weekend task but isn't that difficult. I just realized I am assuming your car is a 240. Is it a 240 or a 7/940?

EDIT: Just saw the thread is for a 760. I haven't dealt with a heater core in those cars. I'd assume its similar to a 240. Just mark and label everything as you pull it apart.
 
Sounds like failed heater core or blown hose. Like chronicrhythm posted, take your time and mark everything, take pictures if needed. A heater core replacement takes a weekend to complete.
 
thx.. link to precedure for 760?

Vielen Dank (okay, not Swedish)

I bypassed the core with a 1/2" copper pipe section from my home plumbing stock.:roll:

I drove it for a while in 90+ heat,. with A/C on and some full-throttle events. Temp stayed a bit above half. Puzzling, tho is the readjustment needed in the kickdown cable (bypassed the O/D switch) and there seems too much play in all those throttle cables wound around the 'pulleys' on the manifold butterfly feed, incl. pedal and cruise control lines.

NO leaks detected anywhere and it looks like the two pipes jutting thru the firewall are typical heater core 'leads'.

Confirm there are no rubber sections inside the car?

Does anyone have a link with steps to R/R whatever needs removal to change the heater core?

I read threads where a Four Seasons is best quality or have my local radiator guy recore the stock one.:domo:
 
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I'm not too sure. But from the looks of the R&R procedures on Mitchell there is. What year is your 760? Does it have the PRV or the B230FT?
 
Tis the turbo 4 (230FT).

Prior leaks were rather small and intermittant, perhaps due to little/no need for heat, though, that matters little at this point, as any leaks are internal to the cabin.
 
Thanks for that. Our 760T has the ACC (automatic) control and is probably similar, but surely more complex.

I cut/pasted a lengthy procedure I'd found, have ordered an OEM quality core but will be in no hurry to install it due to numerous other items on my lists.

Your support is amazing and much appreciated. :cool:
 
whalepirot said:
Is that for this thread? (with the extra comments)
Click to expand...
Many of us prefer the lower pressure caps-- less risk of blowing out the heater core or radiator.

In the meantime you can simply bypass your heater core. Fashion a u-bend out of some heater hose and elbow fittings and get the heater core out of the loop.
 
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