NHMJXJ Posted August 2, 2022 Share Posted August 2, 2022 On 6/17/2022 at 8:04 PM, Pete M said: purge air out the temp sensor at the back of the head. Anyone got a picture of this? I'm following this thread with interest. Recently by-passed my heater control valve, then replaced it because the coolant overflow tank would fill and coolant leaked past the cap when the motor was hot. I plan to replace the tank, but wonder if it's air in the system? I never had any trouble until the plastic part of the control valve snapped off. Link to comment Share on other sites More sharing options...
Pete M Posted August 2, 2022 Share Posted August 2, 2022 a picture of the sensor? it's at the very back/top of the head on the drivers side. has a single wire snapped on to the top of it. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 2, 2022 Share Posted August 2, 2022 All replacement caps are crap. Search for the Volvo one. I don't have the part number anymore Link to comment Share on other sites More sharing options...
NHMJXJ Posted August 2, 2022 Share Posted August 2, 2022 39 minutes ago, Pete M said: it's at the very back/top of the head on the drivers side. So ... I remove that, run the motor and purge the air from the system? Link to comment Share on other sites More sharing options...
cruiser54 Posted August 2, 2022 Share Posted August 2, 2022 With a bad cap, ain't nothing gonna fix it!! 10244 is the part number of the cap you need. Fill the bottle to the FULL mark, install the Volvo cap, and go drive it. Link to comment Share on other sites More sharing options...
NHMJXJ Posted August 3, 2022 Share Posted August 3, 2022 15 hours ago, saveevryjp1998 said: if you pay attention to gauges Operative phrase. I have a dummy light cluster. I was reflecting on that in your earlier reply about having a helper. Not much help if there's no gauge. 17 hours ago, cruiser54 said: 10244 is the part number of the cap you need. That appears to be a WalMart special not a Volvo cap. Still, I'll pick one up today because my existing cap doesn't seat. I'll go hand tight and it will skip and spin another revolution. Link to comment Share on other sites More sharing options...
cruiser54 Posted August 3, 2022 Share Posted August 3, 2022 walmart? https://www.ebay.com/itm/400544209675 Advance Auto Parts has them also. Carquest also Link to comment Share on other sites More sharing options...
NHMJXJ Posted August 3, 2022 Share Posted August 3, 2022 37 minutes ago, cruiser54 said: walmart? https://www.walmart.com/ip/Stant-Engine-Coolant-Reservoir-Cap-P-N-10244/199721376 Link to comment Share on other sites More sharing options...
NHMJXJ Posted August 3, 2022 Share Posted August 3, 2022 @saveevryjp1998 @cruiser54 Guys like you guys are what makes this place awesome. Thank you Link to comment Share on other sites More sharing options...
Eagle Posted August 6, 2022 Share Posted August 6, 2022 On 8/2/2022 at 9:31 AM, NHMJXJ said: Anyone got a picture of this? I'm following this thread with interest. Recently by-passed my heater control valve, then replaced it because the coolant overflow tank would fill and coolant leaked past the cap when the motor was hot. I plan to replace the tank, but wonder if it's air in the system? I never had any trouble until the plastic part of the control valve snapped off. Unless you have converted to an "open" cooling system, you don't have a coolant overflow tank. How full do you fill that tank? Link to comment Share on other sites More sharing options...
NHMJXJ Posted August 7, 2022 Share Posted August 7, 2022 On 8/6/2022 at 2:13 AM, Eagle said: How full do you fill that tank? The only cap is on the bottle. When the truck is cold, the fluid is at the lower mark. As far as I know, it's a stock 1988 4.0 system, so is that open or closed? With the exception of the hoses and clamps I've replaced, it all looks original. I've returned home after traveling the 13 miles from work (mixed highway and surface streets) and when I shut the truck down, the tank fills. It bubbles to full. Similarly, I was in the drive through at a local burger joint and I could hear bubbling. The idiot light has never come on and when I open the hood, it doesn't seem to be excessively hot. Link to comment Share on other sites More sharing options...
Eagle Posted August 8, 2022 Share Posted August 8, 2022 The stock 1988 4.0L cooling system is the closed system. The plastic bottle on the firewall is not an overflow catch tank, it's an integral part of the pressurized cooling system. The bottle should not be filled more than halfway when cold -- there's a post inside the bottle, under the cap, to show you the coolant fill level. Coolant expands as it heats up, so the system needs the air space in the bottle to accommodate the expansion. But there shouldn't be any bubbling. That could be an indication of air in the system. Link to comment Share on other sites More sharing options...
87MJJeep Posted August 8, 2022 Share Posted August 8, 2022 I'll throw this experience out there. I had air in my closed system after replacing my water pump. I saw the temp gauge fluctuations and new it had to be due to coolant vs vapor hitting the temp sensor. I tried to let some air out at that sensor, but it was messy. And I had a leaking radiator. I replaced it with an open system radiator. I still had the temp fluctuations. I noticed after each drive, the coolant level at the radiator cap was lower, so I started topping it off after the cool down of each drive. I'd squeeze the upper radiator hose several times slowly, and it would push some bubbles out, too. I did that a few times then I started pulling up on a ramp, so the radiator cap location would be a lot higher. I kept topping it off, but left the cap off. I'd squeeze the radiator hose more as well. I did the ramp thing a 2nd time. By then, I think pretty much all or enough air is out. There are no more temp fluctuations at the gauge, so the sensor is staying wet, and the cooling fan operation is now normal. Link to comment Share on other sites More sharing options...
Classy Comanche Posted August 10, 2022 Author Share Posted August 10, 2022 I tell you, since I went to open system with the Mac tank, catch tank and new aluminum radiator. Best choice ive made thus far. Had a bit of an issue where coolant was....disappearing? Don't have a blown gasket, not burning it and definitely ain't leaking it. But it hit me. It sits in my rad and would spit it back up to the "cold" line🤦♂️. It sucks up and spits out what it needs from the tank. And I didn't realize coolant could do that, so I learned that admittedly. But if you have the option to change over to a open system, do it. Engine runs smoother, cooler and oddly I can tell it's more responsive when I hit the gas. Doesn't lag or feel sluggish anymore either, open system to me feels better and think it feels better since these little renix motors run hotter than motors today at a normal running/idle temp. Which I would actually would like to know? I've been told they run hotter. How hot? My Monte Carlo sits around 195-202° on average Link to comment Share on other sites More sharing options...
Pete M Posted August 10, 2022 Share Posted August 10, 2022 210 is perfectly normal for a renix. efan doesn't come on until (I think) 220? Link to comment Share on other sites More sharing options...
cruiser54 Posted August 10, 2022 Share Posted August 10, 2022 close. 218* Link to comment Share on other sites More sharing options...
Classy Comanche Posted August 10, 2022 Author Share Posted August 10, 2022 Ah interesting! Didn't know that. My fan does kick on when driving eventually. Especially during these high 80's and 90° heat. Definitely good to know Link to comment Share on other sites More sharing options...
NHMJXJ Posted August 27, 2022 Share Posted August 27, 2022 So close ... New bottle? Check New clamps? Check Heater hose? Check Did you look at the hose from the bottle to the tee before you cut it to remove it? Dohhhhh I don't suppose anyone knows if there's a way to fit a 5/8" i.d. heater hose over the bottom of the bottle? If only temporarily. Link to comment Share on other sites More sharing options...
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