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Discussion Starter · #1 · (Edited)
88 RRC (3.5 engine), new to me a few weeks back. Getting it sorted. Long list but a good one.

Replaced t-stat as it was stuck open & replaced some hoses while in there. Now it almost pegs the gauge quickly (I turn it off before it hits red!).

Any tricks from the 3.5 crowd on how I bleed this? (have tried nose up, bled 6 times, get some small bubbles, t-stat does seem to eventually open)

Backstory on why I did all this:
-- Upon my purchase, I noticed it would run 1/4 or so on the temp gauge, and never really any hotter - Replaced t-stat w/ genuine Rover and a few hoses (top & bottom radiator, the two hoses around the water pump into heater pipes). Didn't get to the rear heater pipe hoses yet.
-- Cooling system looked in good shape, no sediment, I took out radiator when I did this and turned it upside down, looked in great shape, no rust/sediment.
-- This truck has the old metal tank, and old skool "no y-hose" system
-- Unrelated: I also replaced all 4 v-belts preventatively (was getting some squeal on cold start) and all vacuum lines.

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Pic of which cooling system parts I have for reference.

Now -- to my problem. The temp gauge which seems to work properly gets close to red really quickly. In 10 mins this morning in driveway idling. And in 5 blocks of driving. I did the normal rad plug / expansion tank off, tried to bleed.

Yesterday, I wasn't getting heat. Today bled it again, now I get some heat inside although I wouldn't describe it as blazing. Maybe an improvement but still gets hot very quickly.

Do I just need to keep bleeding (front right elevated, via radiator cap)?

Top radiator hose does get hot eventually and I get some bubbles occasionally from the burping at the radiator top plug. But not the big "burp" when the stat opens like I'd hope.

I've bled it 6 times now ... which is why I ask. At this point I don't suspect something like head gasket or whatever else... since it was running cool and well before this t-stat replacement. And I'm very careful not to actually run it too hot here while bleeding. My neighbors are annoyed with all the idling in my driveway with "my new project"... sigh.
 

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Discussion Starter · #2 ·
Update: it's now parked uphill on a big hill a few blocks from home, thinking maybe that will coerce things as it cools? I definitely found the most expensive house in the neighborhood to park it in front of lol..
 

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Those two little hoses at the top of radiator next to the plug cap, they could be the wrong way round. Are you certain of refitting same as before?

There are (take cap of to look with a light inside) two different terminal inside usually, and to do different things in self bleed system strategy. If transposed it'll give you a run around in air locking.
 

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Discussion Starter · #5 ·
Thank you. I’m bleeding by (from cold, with nose of car up) undoing the radiator cap, watching coolant and a bubble or two come up, and expansion tank up elevated and cap off.

I carefully watch temp gauge, leave it at idle (no revs) and then when gauge climbs I shut it off. Lather rinse repeat.

Here’s a pic of how those 2 small hoses just under the radiator cap are attached.... top one is going to expansion tank. Other one underneath it goes over to throttle body I believe... That’s how it was when I started. (But perhaps wrong?).
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I bleed them with just the expansion cap off (cold or just warm) but then squeeze as much of the top hose, engine to rad, as much as you and with both hands along it. It should expell air into the expansion tank with you hearing bubbles, then as you release the hose it should suck liquid back into system. Don't let the tank level drop such that it lets air back in.

Keep going at this until it just expells and retracts just liquid (no bubble sound) and usually you'll have purged it. Takes a little perseverance but normally always gets it out.
 

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Discussion Starter · #7 ·
I will give it a go!
 

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Massaging the top hose can definitely help, give it a squeeze to push the air out, let it suck water back in, etc. Does the new thermostat have a small bypass hole in it? The hole should be positioned at 12 o'clock to let the most air possible out. Without one bleeding can be nearly impossible, as the maniold just traps a giant bubble of air and it's a nightmare to get it out.
 

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Discussion Starter · #9 · (Edited)
Thanks much. Now, I've removed the brand new thermostat (which is genuine LR and has the little hole with the jiggle valve), and confirmed it was properly positioned. Spring towards block and jiggle pin pointing up. Then I brought it inside in the pot on the stove, and it started to open right around 90 degrees (so much for 88!). Verified good as I was worried it was bad out of the box.

Then I cut off the jiggle valve since it looked like it would only block the little hole, why not? This was my old mechanic's trick.

Reinstalled thermostat.

Finally, I carefully filled the thermostat housing from the upper radiator hose connection after the t-stat was reinstalled, while rocking the truck back and forth. Lots of bubbles out. Lots. Perhaps this will do the trick.

And then when re-installing the temp gauge sender 1 wire connection, I broke the tab clear off. #$#$&@@##! Clearly it was weak anyways from age.

So I called it a day.... since now I can't tell where my temp is during my bleeding exercise.

I do have an infrared laser temp thermometer I use on a water-cooled turbo Porsche (which as an aside is terrible to bleed the cooling system of too so this is not new to me). I'm guessing I can point at it tomorrow in the daylight to ensure I'm not overheating and see where I am.
 

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Hopefully that solves it, I always get rid of those silly jiggle valves too, not sure their purpose. Luckily that 1 wire sensor is pretty cheap, one of the only cheap bits on these cars!
 

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Discussion Starter · #11 ·
Update: 1 week later.
-- Better in that I now have cabin heat, blazing hot on the ready if I want it.
-- New temp gauge sender installed (thank you Atlantic British for 2 day shipping).
-- But the RRC heats up to about 4/5ths+ on the gauge after 10-12 minutes of driving. Which is too hot.
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Today - I'm now trying this with a pressure bleeder. I definitely see why they revised the heater pipes to have the fill tube in later years...
 

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When I couldn't get the air out of mine, I ended up cutting the heater pipes and splicing in a bleed port on the return side, and an aux temp sender that runs to a digital gauge on the hot side (since I didn't trust the factory gauge). It defnitely made bleeding easier and gives me a much better idea of what the temp actually is!
 

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Discussion Starter · #13 ·
I def have air trapped in the plenum/head area, it's the only thing I can think of. Fan works properly. New stat that opens. New hoses. No leaks. Holds pressure. New temp gauge sender. No head gasket leak.

When the temp gauge is almost full hot (7/8 +) on the gauge, the temps I'm measuring while idling are as follows. Measured on the metal of the radiator.

201 degrees - drivers side top of radiator (where hose goes in)
118 degrees - passengers side bottom of radiator (where lower hose exits)

Those are actually pretty good (201 is slightly higher than my D2 which runs around 195 stable all day long).

I think that's more than enough delta/temperature swing to indicate the radiator's in good shape, right? Also, these temps were dead on stable for 20-30 mins idling once the stat opened. It never actually overheats, just way high the gauge.

Heat works great. Spent 3 hours out there today and then gave up.

Maybe I'll buy a new set of heater hoses w/ the fill tube ?
 

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I'd say that's not a bad idea, it makes it much easier.
 

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Mine is original spec with the high fill point next to plenum in the heater line.

I can't seem to get advantage from it though. You have to be very careful when you open it, not hot, not pressurized, not increase rpm etc. As the block (really on any motor system) benefits from running restriction going out to radiator to increase mechanical heat scavenge within the block, it's difficult to actually use it apart from cold fill.

But I used mine last weekend as id replaced the water pump, and it stll air locked when warming. The coolant naturally runs down into the system as you fill, I filled the last amount slowly until it overflowed the pipe and wouldn't take any more, but on starting there's still something like 2 ltrs space in there.

Thinking about it post refill and run, maybe it would work if installed a chimney on the top rad fill that was at same level, then fill and let air out that way. Presumably it's running down into the block to fill that area, then the water pump and out through bottom hose to fill rad from that end as until the block and heads fill it won't approach the t-stat housing and top hose.
 
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