I know.. I know.

...and yes I searched, and I have a game plan, but I wanted to ask a couple quick questions.

First of all, I just re-did the entire cooling system, water pump, tstat, hoses, radiator, etc.. I bled everything and didn't have the waterfall noises (from past experience, this meant it was VERY well bled since I had done it 3x and still had some noises in the past.)

She hasn't been on the road for almost a year and a half, so in my post-repair inspections I thought the heat was working decently well.

However, I drove it to work yesterday and it was 4 degrees at startup.. engine temps climbed seemingly normal for such a cold day, but heat never really got there - at least not like it used to. I know with the bypass system our discos usually have heat nearly instantly.

Once I drop to idle it gets COLD - almost like the bypass spring isn't working and is just allowing the entire stream through the heater core instead of the bypassed hot/short engine loop.

Even at highway speeds (I keep RPMs below 2k usually) it was mostly "warm" though.

I did notice a slight coolant level drop the other day, so I'm thinking some air has worked its way out, and most likely I have a couple pockets still left - I'll re-bleed it at lunch today.

Has anyone had issues with the Motorrad unit's bypass spring? And outside temps of near-zero shouldn't really impact my heat once she's up to operating temps right?

If anything I remember the Discos run warmer than usual at idle in very cold conditions due to the "sensing holes" in the tstat being in contact with the unusually cold water that just traveled the length of the radiator loop (this was the main design flaw in the system as I recall). The RAVE manual even outlines this I think? That in extreme climates the water is SO COLD by the time it goes through the radiator that it causes the tstat to shut almost completely even though actual engine water temps are above normal.

 

I'll go ahead and ask the obvious questions so that others may help you quicker.


1. Is this your '99 DII?
2. Why was is sidelined for a year and a half?
3. Do you know yet if it has "normal" heat when it's not below - Zero outside?

 

blocked heater core?, what is the temp rating on your coolant?

 

x2, sounds like blocked core. if your stat spring gets screwy, it will affect the flow through the radiator not the bypass flow..(unless it blows up and clogs the y or something crazy)
while running check both lines headed to the core. do they feel like they are circulating coolant? are they both pushing warm ?

 

Yeah shes mine, and it wasn't really pertinent at the time so I didn't bother explaining - there's another thread about it though, front-end collision into DOT bumper (moving truck stopped in road, nowhere to dodge). Didn't hit crash cans, JUST the components/sheet metal so it destroyed everything. I had to cut out the inner finder, new hard lines for brake/PS, replace radiator, AC condenser, trans cooler, oil cooler, PS cooler, clutch fan, aux fan, water pump, hoses, and tstat - cut out, replace/weld entire core support and a tab on the frame.

She's running now, and engine temps seem fine - hoses/pressure is good, I swapped to the green stuff a couple years ago and it has NEW green coolant again now.

The inlet heater core hose is HOT and the bottom is cold. I think the blocked core might be the issue, and the trickle is allowing the hot water in there but the fan (especially at max) just makes it cold by the time it leaves through the outlet hose.

**can someone do me a huge favor and see if BOTH hoses are warm, even if blasting the heat on a cold day? I'd expect even the outlet coolant to still be pretty warm, especially once the heater core gets warm.

Honestly I don't remember much about the heat before, but it was mostly a winter beater when I had my mustang and went through "snowmageddon, snowpocalypse" without any issues, so it must have been fine.

I re-bled the system VERY thoroughly, never noticed any air however, and the problem is the same... by the time I get to work, it's barely warm after stopping for a few seconds.


I have a little 12v fuel pump w/ 3/8" hose barbs on either side. I think I'll just set up a bucket of water, some long hoses, and some adapters for the heater hoses... and flush the thing for a while.

My only issue is that after reading about heat issues on here for a while and doing searches, LOTS of people suggest the flush, but I don't think I've read a single case where it fixed anyones problems? Is this a myth or do the DII heater cores actually clog?

Thanks,
-Alex

 

they should be warm

 

Both right, like very little difference in temps? Thanks that's what I figured.

I need to replace my deathly loud idler pulley tonight (doing all of them) - attempting w/o removing fan... wish me luck. If all goes well I'll give the heater core flush a shot as well.

Does anyone know how thin the fins are? is there something I can run through there that'll loosen up any corrosion?

And again has anyone actually HAD a clogged DII heater core?

Thanks everyone.

 

Figured I'd give some closure to the thread for future searches down the road.

PROBLEM FIXED!!

So I disconnected both heater hoses and made a crazy contraption w/ different hose diameters and some clamps to attach a garden hose to the sink w/ a valve at the end. First I sent it through the OUTLET to back-wash the heater matrix. It seemed to take a long time and at one point I swear the valve was open a good bit and nothing was happening, though it sounded like water WAS flowing so it's possible that a huge amount of air was just stuck in there.

After that initial weirdness, water flowed out fine at same rate as valve/water going in. I switched directions twice and filled up a 5gal bucket. Nothing visible really came out, in fact the coolant looked really good. Due to this fact I didn't really get my hopes up.

BUT almost immediately upon starting the car I could feel a good amount of heat from the vents which only got better once I re-bled / closed cap (after bleeding w/ raised tank and car-off method first).

GREAT heat now, better than ever...

I'm going to venture a guess that after the crash while the coolant lines were off, a large amount of air developed in the heater core. This was probably made worse when I started the engine dry a few months ago for a couple seconds after the crash, just to make sure the engine was good still before proceeding w/ repairs.

I will say though - it probably took those extreme events for that much air to get into the heater core, so people reading this after a search or similar problem should keep that in mind. I've done many coolant "bleeds" (switching to green including entire block drain, changing tstat, changing hoses, etc) and NEVER had this problem.

Too bad this was about 30% of my work tonight - the rest was spent swapping out the tensioner pulley, and the bearing on the upper idler pulley (which worked out great - matched it up to a $22 bearing that Grainger had next day, this was the $137 land rover pulley btw!)

TOO BAD THE SQUEAL IS STILL THERE! So after I replaced my alternator a couple weeks ago I started having a pulley squealing noise.. really bad. Figured some of the PB Blast from my alternator job (the bolts were reallllly in there) killed an old pulley bearing. Well after tonight I realized it started after the alternator job because it WAS THE ALTERNATOR! Somehow spraying lube on the idler pulley made the noise go away but it must have traveled on the belt to the alternator?

I'm super pissed now because the voltage regulator on the alternator was bad out of the box as well. When starting the rover, the battery light stays on and it isn't charging. If you rev it up to 1500rpm the voltage regulator kicks on, lights get brighter and the batt/alternator light goes out. Throw in a fried bearing and I think they replaced the coils, spray-painted the housing and called it a "remanufactured" alternator without replacing / checking the bearing and voltage regulator.

 

Make sure all of the pulleys are in alignment. If they are out just a little the belt will squeal also. For the heat, you may have had something blocking the flow in the core. My truck did the same thing but when I backflushed the heater core I did see a little something come out. It wasn't much but I was collecting the water in a bucket so I could see it. After putting it back together I immediately had heat.


Good to see it's back on the road. I remember the thread of the rebuild.

 

Good to hear, heat is good inside the truck. And I have always had good luck with the mean Green alternators