01 LX470. Starter went out, so while I had the intake off I did a lot of other long overdue maintenance. I had no overheating issues before. Spark plugs, injector seals, and the front and rear water bypass gaskets. I got it all put together and it starts and runs… and then overheats. No heat out of the heaters either. I’ve tried purging air bubbles (letting it run with rad cap off and filling as the level goes down), checked the thermostat to make sure it didn’t magically go out at the same time… other than tearing it apart again and starting over to check everything, I don’t know what I should check first. Any ideas would be appreciated.
Overheating after starter+ service
- Thread starter caoimhe
- Start date
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Trunk Monkey
Moderator
Did you leave something crimped? Something get in the coolant system when you were doing the gaskets?
- Thread starter
- #3
I don’t think so, but something is obviously wrong. I think I’ll be taking it all apart again. Bummer. Thanks
hoser
SILVER Star
I think you have to continue down the path of burping/bleeding your cooling system. You can try burping (your system) on a steep incline (radiator higher than engine). The coolant "funnel kit" is good to have. Adds just a little more pressure when filling the system and raises the high point.
JohnnyUtah2
SILVER Star
- Thread starter
- #6
Okay thank you. Would one of those vacuum coolant system fillers work?
JohnnyUtah2
SILVER Star
I’ve never used one. I used the funnel method. Bought the kit from autozone. It helps you see the burps and fluid exchange from the temperature changes.
- Thread starter
- #8
I’ve tried the funnel a few times now, are the level doesn’t really drop, and then it still overheats. If I leave it too long I actually overflow the funnel.
2001LC
SILVER Star
Assuming you assemble correctly. Which includes thermostat jiggle valve at top. Which is necessary for proper air bleed.
No cabin heat and overheating, after draining coolant. Is sure sign of low coolant level.
Run engine up to operating temp. Take on short drive getting up to 3K RPM. Do a few hard stops, which help to dislodge air bubbles from heater cores.
Park overnight, with front end higher than rear and side to side level.
Open radiator cap 8 hours later, before sun-up heats the air.
Top radiator to the neck and reservoir to high.
Repeat, until no air found in radiator.
No cabin heat and overheating, after draining coolant. Is sure sign of low coolant level.
Run engine up to operating temp. Take on short drive getting up to 3K RPM. Do a few hard stops, which help to dislodge air bubbles from heater cores.
Park overnight, with front end higher than rear and side to side level.
Open radiator cap 8 hours later, before sun-up heats the air.
Top radiator to the neck and reservoir to high.
Repeat, until no air found in radiator.
- Thread starter
- #10
Okay, I've done this several times now and I haven't gotten air in the radiator the last few times, but it still overheats.
When it overheated once I noticed a small bubbling leak from the pipe that comes off the rear bypass and into the heater core. I went ahead and swapped that out even though the cooling system would hold pressure when I pressure tested it.
I also got a vacuum tool and applied a lot of vacuum to the system to try to pull any air out that may have been still in the system. Still overheating.
Swapped out the coolant temp sensor, and the fan clutch thinking that because it runs for 20 mins before overheating it could be a fan issue. Still overheating.
I had already changed the thermostat, but it wasn't OEM and I've experienced bad parts straight out of the box before so I decided to cut the middle out of my old one and put it back in. When I did that the temp eventually got to the red, but fluctuated a lot on the way (sure sign of bubbles). After getting to the red, because it was fluctuating and dropping significantly every few seconds I let it run for quite awhile. It then settled at operating temperature. I thought great, just need to actually get all of the bubbles out and have a proper OEM thermostat in.
I've done that, and had it overheat 3 times the last 2 of which there is no more air in radiator after cool down. I still don't have heat in the cabin, rear included. I disconnected the outflow line from the core while running and I have flow there. I'm not losing coolant. I have flow (as shown by the no thermostat test, pulling the return line off the radiator and the outflow off the heater core). I'm lost. Any other ideas? Or other things to test?
I really appreciate everybody's help to this point.
When it overheated once I noticed a small bubbling leak from the pipe that comes off the rear bypass and into the heater core. I went ahead and swapped that out even though the cooling system would hold pressure when I pressure tested it.
I also got a vacuum tool and applied a lot of vacuum to the system to try to pull any air out that may have been still in the system. Still overheating.
Swapped out the coolant temp sensor, and the fan clutch thinking that because it runs for 20 mins before overheating it could be a fan issue. Still overheating.
I had already changed the thermostat, but it wasn't OEM and I've experienced bad parts straight out of the box before so I decided to cut the middle out of my old one and put it back in. When I did that the temp eventually got to the red, but fluctuated a lot on the way (sure sign of bubbles). After getting to the red, because it was fluctuating and dropping significantly every few seconds I let it run for quite awhile. It then settled at operating temperature. I thought great, just need to actually get all of the bubbles out and have a proper OEM thermostat in.
I've done that, and had it overheat 3 times the last 2 of which there is no more air in radiator after cool down. I still don't have heat in the cabin, rear included. I disconnected the outflow line from the core while running and I have flow there. I'm not losing coolant. I have flow (as shown by the no thermostat test, pulling the return line off the radiator and the outflow off the heater core). I'm lost. Any other ideas? Or other things to test?
I really appreciate everybody's help to this point.
2001LC
SILVER Star
So if flow of coolant coming out heater cores back to engine and you're overheating. Than hot coolant is running through cores (Front & rear). You'd have heat! So this makes no sense?
You mention frt & rear water bypass gaskets. Any chance you somehow created a blockage, in bypass. Say a rag stuffed in to keep debris out, not removed?
You mention frt & rear water bypass gaskets. Any chance you somehow created a blockage, in bypass. Say a rag stuffed in to keep debris out, not removed?
- Thread starter
- #12
This whole thing doesn’t make sense.
I thought that might be it, though unlikely, so when I replaced the rear water bypass (I took everything apart a second time to do so) I obviously checked that one, and checked the front since I was in there again anyway… I didn’t leave anything there.
2001LC
SILVER Star
Have you shot thermostat housing (backside) with IR gun, to confirm overheating?
Thermostat, spring side inward jiggle valve at top?
Did you use anything to stop-up water ports of head to keep debris out, while water by passes off?
If for instance, a shop towel was left in a port. It may have pushed/flowed deep into head/block and no longer visible.
Can you see coolant flow through radiator, with cap off, as engine warms?
You say you saw coolant flow out heat cores. Was this with a clear tube spliced in Or you just pulled off the return hose and some came out??
Thermostat, spring side inward jiggle valve at top?
Did you use anything to stop-up water ports of head to keep debris out, while water by passes off?
If for instance, a shop towel was left in a port. It may have pushed/flowed deep into head/block and no longer visible.
Can you see coolant flow through radiator, with cap off, as engine warms?
You say you saw coolant flow out heat cores. Was this with a clear tube spliced in Or you just pulled off the return hose and some came out??
- Thread starter
- #14
I’ve confirmed overheating. 230 before I turn it off.
Yes to thermostat installed correctly.
I did. It’s unlikely, but possible I left something in, or that a piece tore off that I didn’t notice, but I intentionally left a bit of the rag up so it would be hard to put the bypasses on without removing them. Assuming some blockage did get pushed deep, how would I verify or flush it out?
Yes I can see coolant flow through radiator, I also have differing temps on the upper and lower radiator hoses, and when I applied the vacuum tool it collapsed both hoses.
I just pulled off the return hose. At first it was just a dribble, but when the thermostat opened it flowed pretty good before I reconnected it. Though I just took a temp reading on the inflow and outflow and the outflow isn’t hot. So looks like no real flow after all.
yngmrostrvile
GOLD Star
When you used the airlift tool, did you charge the fill line with coolant then pull the system into a vacuum again?
- Thread starter
- #16
It was a vacuum bleeder tool. I don’t know exactly what it’s called. You hook it up to a compressor and it applies suction to the system to pull the air bubbles out. Then I would disconnect the tool, fill with coolant and repeat. It really didn’t find much air in the system though.
- Thread starter
- #17
Okay, I decided to flush the heater core just to make sure I could get flow. Then I attached a hose to the outflow and let the car warm up. Once warm coolant came dumping out and… I had heat!!
So I hooked everything back up, filled the radiator, and let it run. Overheated again, and no heat. So either I’ve introduced a ton of air into the core again that I have to get out, or I have a flow problem that won’t let coolant leave the core? Does that sound right?
The lack of heat is a symptom, but not the cause of the problem. You could block off those hoses and the truck shouldn’t overheat. Have you physically touched the heater hoses to see if they are hot?
You might also try changing the temp sensor to confirm you’re actually overheating.
You might also try changing the temp sensor to confirm you’re actually overheating.
- Thread starter
- #19
2001LC
SILVER Star
So you introduced air (had heat, then removed hose) into cores, than filled radiator again.
You must also do the 8 hour cool down and top again. It's the heater cores that are most difficult to get air out of. Since the engine coolant level must be full, to get coolant to cores. Than it enters cores and push air back into engine, and we're low in engine again. Topping (getting air out) can take a few days of heating and cooling cycles. When topping you must fill radiator and reservoir.
Also make sure you've a good working radiator cap (new Toy OEM) and no restriction in reservoir hose/cap (i've seen these clogged) all the way to radiator.
Also make sure reservoir hose is straight and drops to bottom of reservoir. I see many, where reservoir hose gets caught on inner shelf and curls upward. The reservoir hose then sucks air back in radiator, even when reservoir appears to have adequate coolant reserve level.
If any air in radiator, the reservoir and radiator cap no longer work properly. The radiator ends up low.
Note: Do not remove rad cap during the 8 hour cool down. Doing so introduces air and system loses vacuum created by cooling. It this vacuum, that draws coolant back into system.
If you're sure; no air in system, reservoir & rad cap working as they should and cabin heaters works. Then after cooling and bring engine back up to op temp again and cabin heaters stops working and air back in system and engine overheats:
You've blockage on engine side, if no air found back in the system. Which since issue began after bypasses off and rags used to block ports, is high on list of possibilities.
Or
System low again, so you've an internal leak. Like head gasket. Which could have happen from overheating after your starter/bypass joint gaskets service.
BTW:
Radiator hoses that collapse during cool down, are past useful life.
Tip: You could use a clear hose to bypass heater cores. Run hose from engine out (rear water bypass pipe on driver side), to inlet (water crossover pipe passenger side). You'd then be able to watch flow of coolant and or air. You'd also eliminate cores as any possible issue.
If you'd like to talk on the phone. Post you phone number in the PM you started, I call first chance I get!
You must also do the 8 hour cool down and top again. It's the heater cores that are most difficult to get air out of. Since the engine coolant level must be full, to get coolant to cores. Than it enters cores and push air back into engine, and we're low in engine again. Topping (getting air out) can take a few days of heating and cooling cycles. When topping you must fill radiator and reservoir.
Also make sure you've a good working radiator cap (new Toy OEM) and no restriction in reservoir hose/cap (i've seen these clogged) all the way to radiator.
Also make sure reservoir hose is straight and drops to bottom of reservoir. I see many, where reservoir hose gets caught on inner shelf and curls upward. The reservoir hose then sucks air back in radiator, even when reservoir appears to have adequate coolant reserve level.
If any air in radiator, the reservoir and radiator cap no longer work properly. The radiator ends up low.
Note: Do not remove rad cap during the 8 hour cool down. Doing so introduces air and system loses vacuum created by cooling. It this vacuum, that draws coolant back into system.
If you're sure; no air in system, reservoir & rad cap working as they should and cabin heaters works. Then after cooling and bring engine back up to op temp again and cabin heaters stops working and air back in system and engine overheats:
You've blockage on engine side, if no air found back in the system. Which since issue began after bypasses off and rags used to block ports, is high on list of possibilities.
Or
System low again, so you've an internal leak. Like head gasket. Which could have happen from overheating after your starter/bypass joint gaskets service.
BTW:
Radiator hoses that collapse during cool down, are past useful life.
Tip: You could use a clear hose to bypass heater cores. Run hose from engine out (rear water bypass pipe on driver side), to inlet (water crossover pipe passenger side). You'd then be able to watch flow of coolant and or air. You'd also eliminate cores as any possible issue.
If you'd like to talk on the phone. Post you phone number in the PM you started, I call first chance I get!
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