Fitting larger tyres cause overheating?

[mk_mike]

Hi guys,

I've been told the overheating problem i'm having at the moment is because i've fitted 33" tyres up from 31" to my Triton. This doesn't sound right to me and i think there is another problem. It only overheats on the highway above 70-80kph. V6 manual.

Any thoughts?

[dogbreath_48]

Just looking at your pic - have you pulled the radiator out and given it a really good clean?

[mk_mike]

yup. Radiator was removed and cleaned- while i was at it i fitted a new genuine thermostat and new coolant. also cleaned out the ac condensor. i removed the spotlights from in front of the grille as well in case it was an air flow issue.

[joeblow]

33's and standard gearing? if so it can cause overheating as the engine is working much harder to turn the rubber.

[-Scott-]

I'm not sure what causes your problem, but it's not your tyres. I have similar engine (6G72) and (I presume) a similar cooling system, and have no problems with cooling on 33" tyres - fast or slow, heavy or light load, on 40+ degree days. That's after I did the body lift, didn't move the radiator, but did remove half the fan shroud.

Silly question, but are you sure it's really overheating? I had a Magna temp sender in my Sigma, and it was a real worry. With the Sigma sender, everything behaves as expected.

Next, I'd have to wonder if the water pump is pumping properly - but I can't imagine what would stop it. Can you back-flush the block?

[Tomo_89]

Sounds like a head gasket... what about the water pump? working it a little bit harder shouldn't cause it to over heat

[mk_mike]

33's and standard gearing? if so it can cause overheating as the engine is working much harder to turn the rubber.

i can understand that, but how much harder would it have to work? could you compare it to towing a camper trailer with the standard size tyres? surely that would be more load on the engine?

[mk_mike]

I'm not sure what causes your problem, but it's not your tyres. I have similar engine (6G72) and (I presume) a similar cooling system, and have no problems with cooling on 33" tyres - fast or slow, heavy or light load, on 40+ degree days. That's after I did the body lift, didn't move the radiator, but did remove half the fan shroud.

Silly question, but are you sure it's really overheating? I had a Magna temp sender in my Sigma, and it was a real worry. With the Sigma sender, everything behaves as expected.

Next, I'd have to wonder if the water pump is pumping properly - but I can't imagine what would stop it. Can you back-flush the block?

yeah i've done the modded fan shroud thing as well after the body went up.
i'm sure its overheating. nothing has changed sender wise, its still the standard triton sender, and when the guage goes up it starts weeping out the bottom radiator connection because of the higher pressure.

water pump could be an issue- is there some way of testing for that?

[joeblow]

CAN cause, not WILL cause. lots of other factors too. better off getting a specialist to have a quick look.

[mk_mike]

Sounds like a head gasket... what about the water pump? working it a little bit harder shouldn't cause it to over heat

what do i look for if it's a head gasket? the motor has a slight miss when accelerating down low in the rev range. and theres also an audible ticking noise upon acceleration as well which i thought might be a flange gasket. i asked for all this to be checked at the service last week and got the usual response-

me- "what did you find?"
Mechanic- "not sure-didnt really play up for us"
Me- "did you take it out on the highway?
Mechanic-"no just a basic road test"

Frustrating.

[joeblow]

ahh....mechanics. hope they did a pressure test.

[-Scott-]

Sounds like a head gasket... what about the water pump? working it a little bit harder shouldn't cause it to over heat

what do i look for if it's a head gasket?

Milky oil.
Oil in the radiator (greasy deposits on the underside of the cap, on the top surfaces inside the top tank.)
Most mechanics should be able to check for combustion gases in the radiator.
Compression test may show something, but be farked pulling the plugs! A "de facto" compression test can be done by monitoring current during cranking - won't tell you outright figures, but you can see if one or two cylinders are way down. Motoring organisation did it for me as part of a pre-purchase inspection.

[mk_mike]

Sounds like a head gasket... what about the water pump? working it a little bit harder shouldn't cause it to over heat

what do i look for if it's a head gasket?

Milky oil.
Oil in the radiator (greasy deposits on the underside of the cap, on the top surfaces inside the top tank.)
Most mechanics should be able to check for combustion gases in the radiator.
Compression test may show something, but be farked pulling the plugs! A "de facto" compression test can be done by monitoring current during cranking - won't tell you outright figures, but you can see if one or two cylinders are way down. Motoring organisation did it for me as part of a pre-purchase inspection.

theres no oil in water or vice versa. everythings pretty clean in that regard. methinks i will have to bite the bullet and take it to the local Mitsi dealer.

[steven101]

Something that i didnt see an answer to here... Is there a chance it was all ready overheating before you installed the larger tires and now that you have installed the larger 33" tires that it has made the problem worse? When you installed the new tires did you change any other features on the car?

[mk_mike]

Something that i didnt see an answer to here... Is there a chance it was all ready overheating before you installed the larger tires and now that you have installed the larger 33" tires that it has made the problem worse? When you installed the new tires did you change any other features on the car?

it did overheat once before the new tyres went on. nothing else was changed after the 33's went on though.

[DamTriton]

I'm kind of thinking about a sus radiator cap (blowing off at too low a pressure). This would allow the pressurised water to become steam in the cooling system hot spots, exacerbating the overheating of surronding areas, and allowing the steam to be expelled from the lower radiatotr hose weaknesses.

Try a $15 fix of a new radiator cap...

[daveo]

theres no oil in water or vice versa. everythings pretty clean in that regard. methinks i will have to bite the bullet and take it to the local Mitsi dealer.

dunno about mitsu dealers but i've never had any luck with toyota dealership servicing (been screwed by 3 different ones!). i now go to Motorcare at bowen hills, far better and cheaper too. they specialise in 4wds and especially pajeros - maybe give them a call?? 32524039. might be albe to steer you to a cheap solution.

[NJV6]

When your radiator was removed was it done properly, ie the top and bottom tanks taken off and rodded? Even after a fluch a radiator can be well blocked.

Mitsubishi's have very good cooling systems so something is quite amuk.

[WOZ]

I`ve found this before, Check that the presured t belt tentioner isn`t cactus, water pump is driven of back (smooth) side of t belt and are prone to slipping. Bigger tyres= more load on engine , more demand on cooling system.

[Ruffy]

All the symptoms you've described point towards the problem being engine load related so it's a heat transfer issue. For one reason or another the radiator isn't transferring enough heat.
You've had the radiator cleaned which we can anticipate has illiminated the radiator being at fault. That leaves either air flow or coolant flow.

If it has aircon are the fins on the A/C condensor clean. If you mean through mud the A/C condensor can get blocked. Because it is infront of the radiator it obviously blocks air flow to it.
Is the fan coupling working ok? The fan cluth will be working on and off when you are on the highway, it needs to work to match the air speed flowing through the radiator. If the fan clutch doesn't lock up that could be your problem.
Thay are the two most likely scenarios. After that i'd be looking at water pump flow etc.
Good luck, Dan

[bazzle]

I'm not sure what causes your problem, but it's not your tyres. I have similar engine (6G72) and (I presume) a similar cooling system, and have no problems with cooling on 33" tyres - fast or slow, heavy or light load, on 40+ degree days. That's after I did the body lift, didn't move the radiator, but did remove half the fan shroud.

Silly question, but are you sure it's really overheating? I had a Magna temp sender in my Sigma, and it was a real worry. With the Sigma sender, everything behaves as expected.

Next, I'd have to wonder if the water pump is pumping properly - but I can't imagine what would stop it. Can you back-flush the block?

yeah i've done the modded fan shroud thing as well after the body went up.
i'm sure its overheating. nothing has changed sender wise, its still the standard triton sender, and when the guage goes up it starts weeping out the bottom radiator connection because of the higher pressure.

water pump could be an issue- is there some way of testing for that?

It should never leak. Something is wrong. The cap should expel long before any fittings leak. Fix the connection 1st. It may be stopping system from pressurising properly.

Bazzle

[thehanko]

I'm not sure what causes your problem, but it's not your tyres. I have similar engine (6G72) and (I presume) a similar cooling system, and have no problems with cooling on 33" tyres - fast or slow, heavy or light load, on 40+ degree days. That's after I did the body lift, didn't move the radiator, but did remove half the fan shroud.

Silly question, but are you sure it's really overheating? I had a Magna temp sender in my Sigma, and it was a real worry. With the Sigma sender, everything behaves as expected.

Next, I'd have to wonder if the water pump is pumping properly - but I can't imagine what would stop it. Can you back-flush the block?

yeah i've done the modded fan shroud thing as well after the body went up.
i'm sure its overheating. nothing has changed sender wise, its still the standard triton sender, and when the guage goes up it starts weeping out the bottom radiator connection because of the higher pressure.

water pump could be an issue- is there some way of testing for that?

It should never leak. Something is wrong. The cap should expel long before any fittings leak. Fix the connection 1st. It may be stopping system from pressurising properly.

Bazzle

x2 and ensure there isnt a blocked core or something stopping it flowing and causing excess prssue to build up in that pipe. etc

[lump_a_charcoal]

Take the thermostat out and see if the problem continues... remember to put it back in, but drill a 4 mm hole in it first.

[RED60]

Put 31s back on and see if prob persists. Sounds like it's not just the tyres to me tho...

[-Scott-]

when the guage goes up it starts weeping out the bottom radiator connection because of the higher pressure.

It should never leak. Something is wrong. The cap should expel long before any fittings leak. Fix the connection 1st. It may be stopping system from pressurising properly.

Bazzle

x2 and ensure there isnt a blocked core or something stopping it flowing and causing excess prssue to build up in that pipe. etc

If the system is pressurised then it will be above atmospheric pressure everywhere, although that point (suction line into the water pump) should have the lowest pressure in the system. You need to replace that hose, which means the radiator needs to be drained again. While you're doing that, try backflushing the block to see what sort of flow you're getting.

[Yom]

dunno about mitsu dealers but i've never had any luck with toyota dealership servicing (been screwed by 3 different ones!). i now go to Motorcare at bowen hills, far better and cheaper too. they specialise in 4wds and especially pajeros - maybe give them a call?? 32524039. might be albe to steer you to a cheap solution.

if they're a 4wd workshop, why do they specialise in pajeros?

[-Scott-]

dunno about mitsu dealers but i've never had any luck with toyota dealership servicing (been screwed by 3 different ones!). i now go to Motorcare at bowen hills, far better and cheaper too. they specialise in 4wds and especially pajeros - maybe give them a call?? 32524039. might be albe to steer you to a cheap solution.

if they're a 4wd workshop, why do they specialise in pajeros?

Doh! You missed the compulsory "wanker" reference. Take another shot.

[eighty8]

yup. Radiator was removed and cleaned- while i was at it i fitted a new genuine thermostat and new coolant. also cleaned out the ac condensor. i removed the spotlights from in front of the grille as well in case it was an air flow issue.

Was the radiator cleaned from the outside only, as in hosed off externally to remove mud?, or have the top and bottom tanks been removed and the core itself been cleaned internally?.

If the radiator has'nt been properly cleaned out that could well be the cause.

[zagan]

If the lower pipe is weeping then I would think the pipe is weak (sucking closed) or weeps when it's stopped but squirt/mist out hot water when under load and probably needs to be replaced maybe the metal band is loose or needs to be replaced as well.

Have you checked the rad water bottle is it always empty? if so then you have a leak some where in the system.

I had a slight crack in the top pipe which was leaking water on to the fuel pump and seemed to be making it leak, it seems to have come fine once I replaced the pipe.

So maybe you'd be best to replace the top and bottom pipes re fill making sure there's no air bubbles, that will cause heat problems as well, and see how things go.

maybe do a fluch of thw whole system too to make sure there's no rust and crap in the block etc.

[zagan]

dunno about mitsu dealers but i've never had any luck with toyota dealership servicing (been screwed by 3 different ones!). i now go to Motorcare at bowen hills, far better and cheaper too. they specialise in 4wds and especially pajeros - maybe give them a call?? 32524039. might be albe to steer you to a cheap solution.

if they're a 4wd workshop, why do they specialise in pajeros?

oh, it could be a 4wd or something?

lol