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M13A engine Overheating
- Grasshopper
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12 Dec 2023 18:04 #252827
by Grasshopper
The only benefit of age is experience.
M13A engine Overheating was created by Grasshopper
Hi All. I would appreciate any ideas on solving this over heating problem.
The Jimny comes up to operating temperature reasonably quick and continues slowly to an overheat situation, the radiator header tank is hot although the heat is not transmitting down and the overall radiator remains cool. To-date I have taken the following action. This obviously suggests there is no flow of coolant.
1) Replaced the therrmostat
2) Removed/inspected the water pump all good. On replacing made sure of drive belt tension.
3) Removed and flushed radiator. Water flows through ok.
4) Replaced radiator pressure cap.
5) Replaced temperature sensor (unlikely but in case)
There is no visible signs of oil or coolant mixing in the set up. I have had my Jimny thirteen years and Know it's little quirks but this one has me beat.
Thank you
Dave
The Jimny comes up to operating temperature reasonably quick and continues slowly to an overheat situation, the radiator header tank is hot although the heat is not transmitting down and the overall radiator remains cool. To-date I have taken the following action. This obviously suggests there is no flow of coolant.
1) Replaced the therrmostat
2) Removed/inspected the water pump all good. On replacing made sure of drive belt tension.
3) Removed and flushed radiator. Water flows through ok.
4) Replaced radiator pressure cap.
5) Replaced temperature sensor (unlikely but in case)
There is no visible signs of oil or coolant mixing in the set up. I have had my Jimny thirteen years and Know it's little quirks but this one has me beat.
Thank you
Dave
The only benefit of age is experience.
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12 Dec 2023 18:26 #252829
by fordem
Replied by fordem on topic M13A engine Overheating
I suspect a blocked heater core - temporarily bypass it with a length of hose so that coolant can flow and see if that makes a difference.
On the M-series engines, the thermostat is on the return or cool side of the loop, and it is dependent on flow through the heater to open it, if the flow through the core is restricted, the thermostat doesn't open, so there is no flow through the radiator and the engine overheats.
On the M-series engines, the thermostat is on the return or cool side of the loop, and it is dependent on flow through the heater to open it, if the flow through the core is restricted, the thermostat doesn't open, so there is no flow through the radiator and the engine overheats.
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12 Dec 2023 18:27 #252830
by Phaeton
Replied by Phaeton on topic M13A engine Overheating
I know it's a real PITA having only just done mine, but I would take the thermostat out & try again, as replacing it cured mine but you say you've already changed it.
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12 Dec 2023 20:27 - 12 Dec 2023 20:38 #252834
by Scimike
Yokohama Geolanders, Sony head unit, NAUTILUS Air Horn, DRL conversion, Rear cargo space, Elvis Bobblehead, transfer Guard, Indian hanging Elephant, Koni Heavy track dampers, Custom SS exhaust, Voodoo Doll, Adventure Rack with LED ight bar, vintage ERIBA caravan usually attached (yes it's slow)
Replied by Scimike on topic M13A engine Overheating
I have not had reason to work on my Jimny cooling system, so the following is based on my classic car knowledge rather than Jimny direct, so those that know please correct anything that's not applicable to the Jimny.
Thermostat
Cooling systems tend to flow hot water into top of radiator, cool water out of bottom and into the engine (correct for Jimny?)
The top flow is held back by the thermostat, so during warm up very little water flows through the radiator as the thermostat is closed. So if the thermostat is closed the top hose will be cool. In reality a small amount of water flows past the thermostat to prevent air lock and allow it to work, so the top hose may get warm. When the thermostat opens the top hose will be very hot, you can tell the difference if you are prepared to hold the hose as everything warms up.
So stays warm - probably a stuck thermostat
Burn your hand hot, something else.
Radiator
Assuming the thermostat is open you should feel heat across the entire matrix. If you can't or it's patchy then it could be a blocked core. If the core flows ok it's still possible on an older radiator for the fins to become thermally insulated from the water tubes, simply caused by corrosion, so the radiator is inefficient. Fins falling off or fin damage can be a sign of this.
The water pump.
They tend to spring a leak before they stop working, but a cooling system that's been run without antifreeze for some time may be corroded. This corrosion can impact the efficiency of the pump impeller, this in severe cases stops the flow through the radiator. Difficult one to evaluate.
Viscose fan.
When you start a Jimny from cold ( with Air conditioning fitted) the Air Con fan will spin, after about 30 seconds it will slow down. This is because the viscose fan coupling is still engaged from the last use, the connected cooling fan draws air through the radiator, hence the AC fan spins in sympathy. As it disengages as the engine is cold, it's stops spinning the cooling fan, hence the AC fan stops spinning.
If you don't see the AC fan spin (AC off!) it's possible the viscose coupling is not working as it should. This can cause overheating, but you radiator should still get hot. This fan spin only applies if you have driven it (upto operating temp) beforehand, let it fully cool (overnight) and start it from cold.
I take it it's not loosing any coolant? If it is then that's possibly something else.
Thermostat
Cooling systems tend to flow hot water into top of radiator, cool water out of bottom and into the engine (correct for Jimny?)
The top flow is held back by the thermostat, so during warm up very little water flows through the radiator as the thermostat is closed. So if the thermostat is closed the top hose will be cool. In reality a small amount of water flows past the thermostat to prevent air lock and allow it to work, so the top hose may get warm. When the thermostat opens the top hose will be very hot, you can tell the difference if you are prepared to hold the hose as everything warms up.
So stays warm - probably a stuck thermostat
Burn your hand hot, something else.
Radiator
Assuming the thermostat is open you should feel heat across the entire matrix. If you can't or it's patchy then it could be a blocked core. If the core flows ok it's still possible on an older radiator for the fins to become thermally insulated from the water tubes, simply caused by corrosion, so the radiator is inefficient. Fins falling off or fin damage can be a sign of this.
The water pump.
They tend to spring a leak before they stop working, but a cooling system that's been run without antifreeze for some time may be corroded. This corrosion can impact the efficiency of the pump impeller, this in severe cases stops the flow through the radiator. Difficult one to evaluate.
Viscose fan.
When you start a Jimny from cold ( with Air conditioning fitted) the Air Con fan will spin, after about 30 seconds it will slow down. This is because the viscose fan coupling is still engaged from the last use, the connected cooling fan draws air through the radiator, hence the AC fan spins in sympathy. As it disengages as the engine is cold, it's stops spinning the cooling fan, hence the AC fan stops spinning.
If you don't see the AC fan spin (AC off!) it's possible the viscose coupling is not working as it should. This can cause overheating, but you radiator should still get hot. This fan spin only applies if you have driven it (upto operating temp) beforehand, let it fully cool (overnight) and start it from cold.
I take it it's not loosing any coolant? If it is then that's possibly something else.
Yokohama Geolanders, Sony head unit, NAUTILUS Air Horn, DRL conversion, Rear cargo space, Elvis Bobblehead, transfer Guard, Indian hanging Elephant, Koni Heavy track dampers, Custom SS exhaust, Voodoo Doll, Adventure Rack with LED ight bar, vintage ERIBA caravan usually attached (yes it's slow)
Last edit: 12 Dec 2023 20:38 by Scimike.
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12 Dec 2023 22:14 #252836
by Grasshopper
The only benefit of age is experience.
Replied by Grasshopper on topic M13A engine Overheating
Thanks for your quick response guys.
Scimike your understanding of water circulation direction through radiator etc is very much inline with mine (retired heavy truck fleet engineer) however I was aware the M13A engine thermostat is down flow of the radiator as Fordem has stated.
What I did n't know is the thermostat opening is reliant on water flow through the heater matrix. Considering the high temp in my system I must admit I have been surprised by the only mild heat blown into the cab area. So may be that's the answer.
Need to get my head around what happens when you close the heater core control though (summer use)
Dave
Scimike your understanding of water circulation direction through radiator etc is very much inline with mine (retired heavy truck fleet engineer) however I was aware the M13A engine thermostat is down flow of the radiator as Fordem has stated.
What I did n't know is the thermostat opening is reliant on water flow through the heater matrix. Considering the high temp in my system I must admit I have been surprised by the only mild heat blown into the cab area. So may be that's the answer.
Need to get my head around what happens when you close the heater core control though (summer use)
Dave
The only benefit of age is experience.
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13 Dec 2023 00:51 #252838
by Grasshopper
The only benefit of age is experience.
Replied by Grasshopper on topic M13A engine Overheating
Ah !
Had n’t realised the heater matrix was permanently open flow.
Had n’t realised the heater matrix was permanently open flow.
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13 Dec 2023 05:44 #252839
by Lambert
Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
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Replied by Lambert on topic M13A engine Overheating
I hate to be the bearer of bad news but you have the same symptoms as I did when my head gasket failed. I kept telling myself it was something else and nursed it with many new parts for nearly 3 years but unfortunately when an m13 engine overheats it takes its head gasket with it.
Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
ADOS Attention Deficit Ooooh Shiny!
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15 Dec 2023 08:46 #252889
by oldgazzer
Replied by oldgazzer on topic M13A engine Overheating
Can I ask what action you took in regards to head gasket failure. I have exhaust gasses in my coolant and everything points to the head gasket.
Did you replace the gasket? Or did you do something else such as a sealer or even an engine swap.
My Jimny has over a 130,000 miles on the engine and my dilemma is get rid or throw more money at it.
Did you replace the gasket? Or did you do something else such as a sealer or even an engine swap.
My Jimny has over a 130,000 miles on the engine and my dilemma is get rid or throw more money at it.
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15 Dec 2023 12:42 #252891
by Lambert
Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
ADOS Attention Deficit Ooooh Shiny!
Replied by Lambert on topic M13A engine Overheating
Took it to my tame garage and had the head skimmed and a new gasket.
Temeraire (2018 quasar grey automatic)
One of the last 200ish of the gen3s, probably.
ADOS Attention Deficit Ooooh Shiny!
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17 Dec 2023 23:05 #252916
by Grasshopper
The only benefit of age is experience.
Replied by Grasshopper on topic M13A engine Overheating
Sorry folks I that I have n't given a update of Fordem's diagnoses; been away and now trying to catch up on things. Fortunately I have a big old Volvo that is standing in for the Jimny.
Love the old Volvo but it cant do Jimny's job.
Love the old Volvo but it cant do Jimny's job.
The only benefit of age is experience.
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18 Dec 2023 19:36 #252926
by Busta
Replied by Busta on topic M13A engine Overheating
I would definitely go the engine swap route if the head gasket has gone on a high mileage 1.3. Its very little extra work or expense for a very worthwhile upgrade.
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21 Dec 2023 21:22 #252995
by Darthblaker7474
Replied by Darthblaker7474 on topic M13A engine Overheating
I'm assuming it's not losing coolant/boiling over?
You say you have a lack of heating in the cab, try hitting the heater matrix box firm but gently with rubber mallet and see if you can
get some heat going. If you can this probably means it's blocked, contributing to the over heating.
Mine was doing this too, which ultimately lead to the head gasket going slowly, boiling the coolant too.
You say you have a lack of heating in the cab, try hitting the heater matrix box firm but gently with rubber mallet and see if you can
get some heat going. If you can this probably means it's blocked, contributing to the over heating.
Mine was doing this too, which ultimately lead to the head gasket going slowly, boiling the coolant too.
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