[LanceL]

The cliff idea would work temporarily, provided you drove off backwards (nose up to get that bubble out), however there may be some gravitationally-induced side effects resulting from the effort that may introduce new challenges. It's a repair strategy I myself have pondered on numerous occasions.

 

[LanceL]

Could always just find a dam to climb

 

[LanceL]

Did you try backfilling through the top hose? I did that once when I had a bubble issue. Disconnected from rad, (put a spare chunk of hose I had on the rad side pointed upwards so it didn't all pour out) then lifted the top hose and poured coolant slowly (it drains though that little bypass hole in the thermostat). Slow, but I got a good amout to go in that way (and heard bubbling). Reconnecting was messy, but worked. Had a helper who covered the top rad port with thier hand while I prepared myself to reconnect the hose and then "3....2......1......go go go get on there!!!!"

 

[RRLondon]

Thermostat replacement: jiggle pin and bleeder valve

Discover the importance of bleeding the cooling system after thermostat replacement, the function of the thermostat jiggle pin, and more.

www.gatestechzone.com

Worthwhile considering.

 

[RRLondon]

I've manufactured and used this type of thing before Pro Alloy swirl pot: Ford Sierra Cosworth PROSP5 (on these V8 when racing) a little difficult to fit in due the the relative height of top hose ends.

Effectively bleeds out air to vent into expansion tank.

BUT, that's what the system is trying to do with that jiggle pin arrangement in the thermostat. It should allow any steam pockets to exit even with stat closed, then collect in the radiator top and pass out the vent to the expansion tank in the original fitment equipment.

It's possibly why it didn't have this ongoing effect before when running too cool (stat permanently open) but now comes into existence with new stat and it's attendant flow.

 

[nashvegas]

Today's riveting update:

-- Went and bought a combustion leak detector and fluid yesterday. Did the combustion leak test - and passed. No combustion leaks into coolant. So hopefully that rules out the head gaskets/cracked block/etc. I just couldn't not know.

-- Then I took off the small radiator to upper intake manifold hose (remember I bypassed the throttle heater). Revved the engine and squirted coolant yards sideways to try to move an airlock out. No change.

-- I was thinking perhaps my water pump was on the way out or the fins had corroded off... but based on the impressive distance the water shot out, I think it's safe to say it's pumping well.

I will beat this. Even if it means I need to buy the vacuum filling tool, and an air compressor (*which I don't have at this house), I will. I think that's probably the best course of action. Side note: we managed to move the CDL/H-N-L lever on a test drive (just couldn't leave well enough alone, could I?) and now the neutral bleeping noise won't stop, in any position. Which is fun and surprisingly loud persistent alarm that is.

 

[portofino88]

I have an 88 as well, and I've been through the same thing EXTENSIVELY. Here's what I needed to do. When I purchased the truck, the gauge used to always hover at the 7/8 mark. NEVER overheated, no evidence of gases in coolant. I replaced my radiator (with an aluminum), fan clutch, hoses, water pump, bled and bled and bled the system. The gauge used to always hover around 1/2, sometimes reaching that 7/8 mark. I found my old coolant tank had pinhole leaks at the tiny inlet and I was getting air, so I installed a good used one and fixed the issue with the air bubbles. I figured the thermostat was bad. So I followed everyone's advice and spent money on the best OEM thermostat I could find. And sure enough, the engine ran even hotter! Frustrated, I went to O'Reilly's, picked up a 165 degree thermostat, and sure enough now the temperature gauge runs at about 1/3, sometimes going on 1/2 after getting off of the freeway. This is even in 100+ degrees F in southern California. The only drawback if any is if you're living in the NE or NW I would definitely use a 175 degree stat, so that you get some heat. As long as you have the OEM temperature stat in there, no matter what you do to get air out, etc. nothing will change the temperature that the truck runs at. It's the only thing that worked for me!

 

[portofino88]

This was where it used to sit when I got it, and with a new OEM thermostat

This is after changing the radiator, pump, hoses, etc.

This is now where it sits with the 165 degree thermostat, 90 degrees outside

This is in cold (for SoCal) weather, 40 degrees F. No running/closed loop issues.

 

[nashvegas]

BTW thanks... everyone has been very helpful. Both for 'therapy' and 'tactics' !! PS Portofino88, I'm jealous of your gauge illuminations actually working. On my list to fix.

Now, I've drained and then vacuum re-filled the coolant with a couple Harbor Freight purchases that worked pretty well. Fun to watch the upper rad hose collapse under vacuum.

Then found the steepest spot I could find on pavement in east Portland to bleed it on, in Mount Tabor. No change.

This morning, I took the RRC 50 miles north of here into the mountains north of Camas WA (Skyline trail if anyone knows it), where I got it about as vertical an incline as I could a few times, and attempted to coax bubbles out 3 diff times. No real bubbles, nothing of note happened.

More importantly, I had some fun in Low Range, with CDL on and off, and was quite pleased w/ how it did off-road. I like this truck! There's a very annoying rear suspension rattle that I've managed to make 10x worse though. Praying that it wouldn't die where there was no cell signal because then I'd be hearing about "the 4th tow in 2 months on that Rover I told you not to buy".

Temp stayed right at 3/4 the whole time. And I climbed some pretty serious hills/etc. I pushed it, deliberately to see if it would overheat. Nope. Ran brilliantly though.... And after my attempted nose up bleeds... still no change. At one point my bloodhound in the rear was actually sitting on the rear tailgate door carpet the incline was so steep. She got a treat on the ride home. If I can figure out this temp issue, I think my weekend warrior RRC is getting close to being reliable (?).

Multiple times on the trip I checked temps underwood w/ my infrared thermometer... always 194-202, anywhere and everywhere. Lower rad exit temps were 120-140, so pretty happy with the temperature differential (guessing this means my rad is not plugged or crude up, of which I've found no evidence). The hottest temp (202) I saw is right above the gauge sender around the t-stat housing... So even though gauge is higher than I'd like I am convinced I'm not causing damage. More importantly, if that's 202, why is the gauge so high...hmm? Still something up there.

-- I'm now convinced my new aftermarket gauge sender (from Atlantic British) may be just mismatched to the gauge even though it was for 87-89 NA models. Ordered a genuine sender (same part #) and another thermostat for giggles ETC4761 from Rovers North "Thermostat 76C V-8 , 2.5 NA Diesel". It's listed as 165F -- and it's genuine so maybe will be effective.

-- Also, Napa down the road has a 160 Tstat .. I'm going to throw it in today for $16.99 just to see if it changes anything (because I'm too impatient to wait a week for the shipping from Vermont for the above.

AKA. Throwin' parts at it.

 

[Lockettc]

@nashvegas: "AKA. Throwin' parts at it."

Story of my life - my patients for proper diagnostics is quickly overcome by my ADHD and desire for it to be as it was before! : )


You mentioned a fan clutch change... I had to sort through two clutches before I found a 'good' one. One was locked and the other was the same as my failed unit. Happy to send you the 'locked' one as a test subject - it certainly will pull max airflow!!

Also - you may want to try a second temp sender.

 

[LanceL]

I have an interesting theory why the gauge might be off. I have this same misbehaving gauge issue, except even more extreme (I installed a digital gauge that reads from the heater high side to give me accurate temp, so the cluster gauge is just an annoyance right now). My gauge would slowly vary between 3/4 o the gauge to as high as all in the red, despite the IR thermometer showing the motor at a cool and comfortable 180-185. Baffled the hell out of me, went through THREE gauge sending units from different sources (AB, Rovers North, and Rimmer Bros), STILL no change. I discovered something else as well, that my gas gauge was running a little "optimistic" in that one day when I was running a bit low (8th of a tank) I thought "it's only 3 miles to home, I'll be fine" I promptly ran out and needed a helpful rescuer with a gas can. The coincidence between two separate gauges both running "high" made me curious. It turn out, for those of us with the older style gauge cluster (87-89) There is a voltage regulator that lives on the back of the cluster which takes in battery voltage (varying ~13-14V) and outputs a steady 10V as the reference voltage for these two gauges. If the reference voltage is no longer static (and is now higher) this would result in a varying offset to both gauges (making them both read high, and vary a bit). I found a tiny voltage reguator from Pololu (input 3-32V, output programmable 4-12V, 2A) that I ordered and am planning to swap out for the one on my cluster, and hopefully that will correct the misbehaving gauge issue.

 

[LanceL]

Also now I too feel obliged to share a 'cute dog in a rover' pic (forgot the anti-drool protection towel that day)

Followed by 'cat in a rover'

 

[nashvegas]

I have an interesting theory why the gauge might be off. I have this same misbehaving gauge issue, except even more extreme (I installed a digital gauge that reads from the heater high side to give me accurate temp, so the cluster gauge is just an annoyance right now). My gauge would slowly vary between 3/4 o the gauge to as high as all in the red, despite the IR thermometer showing the motor at a cool and comfortable 180-185. Baffled the hell out of me, went through THREE gauge sending units from different sources (AB, Rovers North, and Rimmer Bros), STILL no change. I discovered something else as well, that my gas gauge was running a little "optimistic" in that one day when I was running a bit low (8th of a tank) I thought "it's only 3 miles to home, I'll be fine" I promptly ran out and needed a helpful rescuer with a gas can. The coincidence between two separate gauges both running "high" made me curious. It turn out, for those of us with the older style gauge cluster (87-89) There is a voltage regulator that lives on the back of the cluster which takes in battery voltage (varying ~13-14V) and outputs a steady 10V as the reference voltage for these two gauges. If the reference voltage is no longer static (and is now higher) this would result in a varying offset to both gauges (making them both read high, and vary a bit). I found a tiny voltage reguator from Pololu (input 3-32V, output programmable 4-12V, 2A) that I ordered and am planning to swap out for the one on my cluster, and hopefully that will correct the misbehaving gauge issue.

I've verified my fan clutch... what I found on my truck was an aftermarket unit, it was working, but I replaced w/ a good one and the fan's loud / comes on / I can feel lots of air blowing.

LANCE awesome pets btw. I have the exact same theory, in fact...

1 -I bought a replacement cluster and swapped out this piece top right in the photo below (voltage stabilizer part # PRC5916 which supersedes to a new # that's also NLA)... no change. Sigh. I didn't post about it here tho.
2- Ran permanent jumper wires over the ground trace between the tach, fuel gauge and temp gauge. (all 3 of these points are easy to jumper wire as they are held on by small nuts).... I had noticed that the plastic circuit board had a crack in the trace up to the tach, and my tach and fuel gauge would intermittently drop out if I pressed on the flexible circuit board around that area. The 2 cracks in the trace were so small I could barely see them, but with a magnifying glass it was obvious. Fixed that problem with the tach and fuel gauge which seem to be back to 100% operation. So at least I'm crossing something off my list.

But ...no change to temp gauge. I thought maybe that weird trace crack was affecting the temp gauge since it's in the same trace/circuit and perhaps was causing resistance or something amiss. Also, it's nearly impossible to source good used 87-88 RRC clusters!

 

[nashvegas]

I've bought a VDO temp gauge and VDO sender/adaptors to go into the stock temp sender connector location ... gets here next week. I'll see if that can give me better info. More to come next week.

 

[LanceL]

Hmm that's a serious conundrum then, sorry I didn't see that you'd posted previously about the swapping the voltage regulator. The glowshift gauges I added are now really all I look at, I'm always nervous about temps and pressures so I have two dual gauges, one that does engine and tranny temp, and the other is oil temp and pressure. Definitely agree on the difficulty of finding good 87-89 clusters! There was an '89 that showed up in a local-(ish) pick a part (super rare) and by the time I found it (it had only been there 3 days) all the usual good bits were already gone, picked clean by some other rover fan who knew what they were looking for!

 

[nashvegas]

Well I'll be ....

I installed a VDO "Vision" 250 degree temp gauge today, Used 5/8"-18 VDO 250 degree sender that I had to special order, VDO part # 323422, so no adapter required, and fit right in the stock gauge sender hole with a brass oil plug drain washer (instead of the stock fiber washer which I couldn't find) .

This means I'm measuring engine temperature in the same spot as the temp gauge was, not radiator or radiator hose temp. Note that this VDO sender # 323422 is about 1/4" longer than the standard Rover sender. I was worried it might bottom out, but that was not the case, it fit perfectly.

And look where it is -- on a 20 mile drive this evening, it was between around 175-190 on the gauge, and rock steady. My D2 is 194 all day long, so I'm a bit surprised this is lower, but I'll take it.

Left it in the paper packaging so it wouldn't fall down the radio DIN hole. I've ordered a nice simple 2 gauge DIN mount for older Audis/VW's, and the gauges will go where the radio would go ... I'm adding a VDO 80 PSI oil pressure gauge this week also, as my light is always flickering, or on. When I put my Harbor Freight gauge on it's never dipped below 10/12 PSI at idle. Apparently the stock oil pressure idiot light comes on between 5-8 PSI, so .. I've got a gauge cluster or ground or voltage stabilizer (in gauge cluster) issue I can't figure out. I guess I don't need a radio in this truck until I get it sorted.

Celebrated with a beer picking up dinner. Since I now dare venture more than a few blocks from the house... (missing drivers side mirror, working on window regulator/motor/mirror and replaced the rubber window waist seals today which look cracking good!)

 

[LanceL]

Always nice to have that celebratory beer after sorting out something frustrating! If you do want your radio back at some point, I added my extra gauges in pods down below on either side of the steering wheel. Not directly in line of sight, but easy enough to glance at and they don't interfere with the look of the rest of the dash (analog one is getting replaced with another dual digital gauge).