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Thread: Cooling issues

  1. #1

    Cooling issues

    I have a '89 Chrysler Lebaron T1 with cooling issues. The temperature gauge when driving swings from 1st mark above cool to 3/4 hot and then swings back down to cool repeatedly (car does not overheat). I've changed the thermostat ( with drilled hole ) and made sure all air was purged. When I got home from a twenty mile ride I could open radiator cap and no explosion of radiator fluid when I opened cap, in fact the radiator cap was cool. Both upper radiator & lower hoses feel hot. Radiator fluid has been changed every one to two years. Water pump is three years old and has only 15K miles on it. Any ideas ??

  2. #2
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Cooling issues

    My 89 CSX has been doing this, but it rides very low, then goes up to normal before dropping faster than physically possible to the low spot it likes to ride. I too have observed no problems when looking at the system. I think my problem is the gauge or the sender.

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    See me ride out of the sunset... Turbo Mopar Staff BadAssPerformance's Avatar
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    Re: Cooling issues

    Does it only heat up while driving, like on highway, them cool off when idling? My CSX Clone only gets hot on highway, but not around town. Soon as im off highway it cools off. Put a head gasket on it and saw cracks in head.

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    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: Cooling issues

    I'm curious if both of you are in cold areas of the country, or if this seems worse in the very cold.
    I am seeing something very similar and first noticed in the cold (less than 40F and closer to freezing). I also have a 180F stat, with at least one hole drilled. Always runs just under 180 in the summer, maybe about 177F on a datalog.
    But following a custom aluminum radiator install, this observation seems worse.
    I saw my gauge swinging around as you mentioned, but my datalog was showing lower temp than what the dash gauge would indicate.

    I think the problem is caused by the hole in the T-stat. Between running the heat inside the cabin, and the hole in the stat, both take away from the heat building up inside the engine and the t-stat opening naturally. The cabin heater is probably a big part for me because a 180F stat isn't enough heat, and it dissipates quickly with even that small constant flow through a very efficient radiator, and the heater core. So the t-stat is basically staying closed. Without good flow through the t-stat, I think there may be a hotspot at the gauge sender, so it shows hotter, but the other sensor reads low.
    That's my theory anyway.
    I need to spend some time with mine to make sure I don't have another problem because it seems weird. I may try popping in a 190 or 195 t-stat to see if that fixes it.

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    See me ride out of the sunset... Turbo Mopar Staff BadAssPerformance's Avatar
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    Re: Cooling issues

    Good thinking Wayne. If the engine is not up to temp, the t-stat will not open and when it does it gets a cold slug of coolant from the cold radiator and shuts.

    The bleed hole does hurt this due to the cold water continually flowing in past the t-stat, the t-stat is held closed longer.

    So overshoot and oscillation are likely

    JT
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    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Cooling issues

    I have done away with the 180* T stats for daily drivers. My CSX has a stock 195* unit with no hole I've drilled, and there isn't a bleed hole in this model like I've seen before either. Your idea could very well be the case none the less, as it would explain why I'm seeing an almost instantaneous drop in temps. However, the thing which makes me think it's not what I'm experiencing is that the temp can jump up nearly as fast as it will drop. I clearly need to do some more testing and make note of the time interval between being toward the bottom hash on the gauge and the middle where it should ride.

  7. #7
    See me ride out of the sunset... Turbo Mopar Staff BadAssPerformance's Avatar
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    Re: Cooling issues

    27 years ago a STANT rep came into the parts store I worked at and said from sitting on the shelf they have a crazy high rate of 25% sticky t-stats

    JT
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  8. #8
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Cooling issues

    Quote Originally Posted by BadAssPerformance View Post
    27 years ago a STANT rep came into the parts store I worked at and said from sitting on the shelf they have a crazy high rate of 25% sticky t-stats
    I doubt T stat technology has progressed much in the last 3 decades. I wonder if I should start testing mine before installation? What a pain.

  9. #9
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    Re: Cooling issues

    Quote Originally Posted by cordes View Post
    , as it would explain why I'm seeing an almost instantaneous drop in temps. However, the thing which makes me think it's not what I'm experiencing is that the temp can jump up nearly as fast as it will drop.
    I am sure this is not the case in your case but I did see this behaviour in my DD. The issue was air in the head caused by a few small pinholes in the upper portion of the rad. My Rad pressure tester found the issue. Replaced the rad and the issue went away.
    Regards,
    Miles

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  10. #10
    Super Moderator Turbo Mopar Staff 135sohc's Avatar
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    Re: Cooling issues

    I popped in a moto-rad 192* "oe temp" t-stat in the Shadow a few weeks ago, I was running a 180* and cruising highway speed with it being cold recently it would struggle to reach 160 on the scanner. With the new t-stat it is only marginally warmer, @ 50* outside cruising it still struggles to reach 180. On below freezing days I run a piece of card board in front of the radiator, otherwise it will never warm up.

    Until I switched to the diesel engine spec coolant this was never much of an issue
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    Supporting Member Turbo Mopar Contributor
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    Re: Cooling issues

    Quote Originally Posted by cordes View Post
    I doubt T stat technology has progressed much in the last 3 decades. I wonder if I should start testing mine before installation? What a pain.
    It is not really bad, Place all your Thermostats in a pot of warm water with a thermometer and heat slowly until they open record the temperature. Now cool naturally until they close and record the temp. I test approx. 8 and found one that was slow to respond after several tests, so I tossed it out.
    I was glad I tested my inventory.
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  12. #12
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    Re: Cooling issues

    My R/T does the same temp swing with an undrilled t-stat. Rises to 193/194, drops quickly to 165-170ish, rinse & repeat in cool weather. The dash gauge reflects the change as well. I chalked it up to the fact the t-stat is the last portion of the engine to get coolant and both temp sending units are nearby. The swings tend to get less severe on longer highway drives.

    I did notice when I tested it before installation that it opened quite a bit quicker and a noticeable amount further than any of the other used ones I had in my spare parts bin that I checked at the same time. The others were all drilled units, and I wasn't about to put one of those in after last winter.

    With a drilled 195* unit it struggled to reach 170* in cooler weather but the temp was rock solid @ 190* in warm weather. It tested good in a pot of water, staying closed until 190-195 and closed quickly when put on the counter. I changed it out for a non-drilled unit so that the engine would fully warm up. Had to drive it some last winter when the temps were below 0 and it would barely get over 120* even on the highway cruising in 4th gear to keep the RPMs up; with the drilled t-stat.

    I'm running one of TU's aluminum 3 core GLHS replacement radiators in the car with plenty of baffling to force air through it and a Volvo S70 2-speed fan behind it.

    With my previous 8V engines I didn't experience the temp fluctuations nearly as much after the initial cycling of the t-stat when running undrilled units, but did noticed the cooler operating temps with drilled units in cold weather.
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  13. #13
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    Re: Cooling issues

    So my question is how big are you guys drilling holes in your thermostat? Are you placing it is it's most vertical position in housing? Idea is to provide an air bleed to remove air from high point in system, and not as a coolant bypass hole. 1/32nd (.031) drill is certainly big enough. I typically drill them even smaller. Either that or actually use the 3/8" vent plug on 8V heads. Doing that, you don't need a drilled thermostat.
    Those running the TU's radiators in L-bodies, the coolant return hose aluminum fitting included with the l-body kit I noticed is very restrictive. Probably less than 1/4 the size of the factory GLHS 5/8" barb on tank. Didn't use this fitting because of this.
    Can always place something in front of radiator like the big rigs do in the cold, if your suspecting the heat exchangers are more effective than the engines ability to produce and retain heat. I do that on my New Yorker during the winter months. Works great.
    Only time I've ever experienced wild temp swings on gauges is when heater core is partially blocked, or someone isn't running any bypass at all. Then scenario like Wayne and JT talked about in post 4 & 5 comes into play.
    Todd

  14. #14
    See me ride out of the sunset... Turbo Mopar Staff BadAssPerformance's Avatar
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    Re: Cooling issues

    Good comment on bypass flow Todd, that is very key to make sure the t-stat is functioning properly. On the 2.4L in the Z I do not have a bypass other than the coolant feed to the turbo which seems to work OK as long as I let it get up to temp.

    Thinking about this more, does anyone have the circuit diagrams for the "pre 1989" and "1989 up" water pump and cooling circuits? Would be interesting to see side-by-side how the changes were made

    JT
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  15. #15

    Re: Cooling issues

    Okay, I think I fixed my problem. I changed the thermostat to a Stant Superstat #45788. Definitely helped. It was a $8.00 thermostat but well worth it. It has a V notch to provide a small initial flow. And has a larger piston and other features that made it worth it.

  16. #16
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Cooling issues

    Glad to hear this issue is resolved Jim.

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    Re: Cooling issues

    Quote Originally Posted by 4 l-bodies View Post
    So my question is how big are you guys drilling holes in your thermostat? Are you placing it is it's most vertical position in housing? Idea is to provide an air bleed to remove air from high point in system, and not as a coolant bypass hole. 1/32nd (.031) drill is certainly big enough. I typically drill them even smaller. Either that or actually use the 3/8" vent plug on 8V heads. Doing that, you don't need a drilled thermostat.
    Those running the TU's radiators in L-bodies, the coolant return hose aluminum fitting included with the l-body kit I noticed is very restrictive. Probably less than 1/4 the size of the factory GLHS 5/8" barb on tank. Didn't use this fitting because of this.
    Can always place something in front of radiator like the big rigs do in the cold, if your suspecting the heat exchangers are more effective than the engines ability to produce and retain heat. I do that on my New Yorker during the winter months. Works great.
    Only time I've ever experienced wild temp swings on gauges is when heater core is partially blocked, or someone isn't running any bypass at all. Then scenario like Wayne and JT talked about in post 4 & 5 comes into play.
    Todd
    Todd you're right. But yet there's so many out there that think that an 1/8" hole is the size to drill.

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    Supporting Member Turbo Mopar Contributor supercrackerbox's Avatar
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    Re: Cooling issues

    Quote Originally Posted by 4 l-bodies View Post
    Either that or actually use the 3/8" vent plug on 8V heads.
    The potential issues with that are A: The steel plug is completely seized into the head, or B: Many heads I've seen don't even have the hole. While it's easy enough to drill and tap, novices may be hesitant to do so. As for the seized plugs, once I find a way to remove them, I always replace them with aluminum plugs from Speedway or Summit.

  19. #19
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    Re: Cooling issues

    Quote Originally Posted by supercrackerbox View Post
    The potential issues with that are A: The steel plug is completely seized into the head, or B: Many heads I've seen don't even have the hole. While it's easy enough to drill and tap, novices may be hesitant to do so. As for the seized plugs, once I find a way to remove them, I always replace them with aluminum plugs from Speedway or Summit.
    Stainless plugs work too. You can always use a fitting like in bottom of radiators, or thumbnail pet---- fittings too. I usually have success getting the originals to break free if you try when engine is fully up to temperature. I see petkock is a bad word.
    Todd
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  20. #20
    Hybrid booster Turbo Mopar Contributor 85lebaront2's Avatar
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    Re: Cooling issues

    Good point, I want to do that on mine but even hot I can't get the plug to move. On blocking part of the radiator, boy does that bring back memories. I had a 1958 F100 with the 223 ci six. In the winter I had a sheet of 1/4" plywood I used to cover about 2/3 of the huge copper/brass radiator used in those trucks. If I didn't, the heater was about as effective as a British car, if you stuck your hand in the defroster vent it might just warm your fingers. Since the Ford gauges of the day were slow to respond I didn't see wild swings, just a slow oscillation on the highway, from just off the peg, to barely below about 1/4 scale, summer it would run about 1/2 scale with a 180° degree thermostat.

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