Previa Overheating Saga

[miti-babe]

Dear All

Since I took ownership of a '91 2.4 GL Previa last July, it's always had some "issues" with it's cooling system...

I noticed soon after buying it that long (over 100 miles), fast (80 mph +) motorway journeys would see the temperature guage souring skywards... :ffs:

A short break would soon have the situation under control and I must say that the threat of an overheating engine has done wonders for my driving license and fuel economy...

However, the problem has persisted and worsened... we've now got a situation where the car overheats on fast or slow journeys and we can only get it under control by turning the cabin heater on... That's warm work in June!

I've decided to "grasp the nettle" and I'm going to sort this problem out once and for all... here's a precis of what I've done so far, followed by what I intend to do... I'll ask some questions at the end, so listen closely now.. B)

First thing was to drain/flush/refill coolant - coldn't get the block drain plug out, so flush wasn't as complete as it could have been... Made no difference anyway..

Next, I considered replacing the thermostat... except the engine runs perfectly most of the time, with the guage needle bang in the middle... when I got underneath to check the 'stat housing, there are two new bolts and signs of instant gasket... I surmised that the previous owner had had this same problem and beat me to the thermostat, so I left it alone...

Next I tried a new (pattern) filler cap... no change

Now, after some investigation on t'internet, :bookworm: I've checked out the viscous coupling, which appears to be cream-crackered... I can't detect any difference in the fan's resistance to me spinning it when the engine is stone cold, or immediately after an overheating incident... It always seems very "loose" and must be slipping like a B*****D!!

I priced the coupling up at Toymota and wasn't suprised that it's £157 +VAT...

I know some folk who have removed & serviced these couplings (seized valve freed off and even refilling the silicon fluid - I wouldn't know where to look for silicon fluid... Is this something girlies get for "top-ups" after a boob job? )

Anyhow... replacing or repairing the coupling would only have the cooling system back to 1991 standards and I would like to improve that situation...

I e-mailed Kenlowe, but they never bothered to e-mail me back... I reckon they could tell by the e-mail that I wasn't about tp part with nearly £200 for a Kenlowe kit... They were right!

So I've bought a nice new 15" electric cooling fan and mount (to fig an MG apparently, so I'll end up with a Previa "Sport") via eBay and I'm planning to modify the Previa system to run with this...

What I need to know now is:

"What temperature the fan should be set to switch on at?"

Incidentally...

I was planning to remove the water pump to inspect the pump vanes (167,000 miles, so the pump may actually be worn out ) While I'm doing that, I was going to have the thermostat housing machined to accept a thermal switch for the new fan... but without a guide to the temperature range, I don't know which donor car/switch to go for...

Anyone else have any clues?

Other imminent plans include: removal of viscous coupled fan and insertion of shorter pulley bolts... modification of OEM fan shroud to accept/mount MG fan and bracketry, removal and full flushing of radiator, filler tank and pipework (I'll get that darn block drain out this time too!)

I'm also planning to install a "manual override" switch for the electric fan... just incase the MG fan hasn't got the CFM capacity that the Previa needs...

I would love to hear from anyone who has modded their Previa/Estima/Lucida/Whatever to run an electric fan... I understand that the conversion also releases more mpg, so there's snother reason to go this way...

Anyone got any hints or suggestions..? :hokus-pokus:

[karllangston]

Hi Jeff

I thought the Idea of Previa ownership was an easy life with a reliable vehicle? you are unlucky if the couplings have gone. be watching closely to see how this one turns out - good luck and bring on the extra prancing horses....

just cleaned out the throttle body - a la one of your previous posts. thought i'd stuffed it when it refused to start on petrol, but got it going on Gas and ragged it down the dual carriageway, now all is good in the land of dual fuel mules. pulling stronger as well!!!

btw do you know what the prefered choice is for autogas systems for the previa now? having trouble getting a Landi Renzo engineer in south wales?

Karl

[miti-babe]

Karl

Well... I modified the fan housing to fit the MG electric fan... but on removal of the OEM viscous fan, I discovered that the fan pulley has an extended centre... this fouled the motor on my MG fan, so I had to revise my nice runner mounts with spacers and then use longer bolts and spacers on the fan motor before I had clearance to make everything fit... :arrgg-matey:

The overheating problem still persists, but the new fan (being operated manually) has the measure of it... We now only have to use the cabin heater ploy after a long high-speed hill climb... <_<

I took the time to take off the thermostat housing... and found that the previous owner had actually gone to the trouble of cutting the 'stat in half, so that the outer frame was still in the housing, but the wax pellet end and valve were removed... Why oh why did the Good Lord think that the world needed that kind of D***HEAD??! :ffs:

My replacement thermostat from Partco wasn't correct, but Motorworld have sorted me out a USA sourced goodie that'll be going in soon....

With regard to the thermostatic switch, I've gotten hold of an intermotor catalogue (e-mailed an enquiry and received their ISS-1 catalogue in the post the following week - Free, Gratis and No charge either... Well Done Intermotor!

I'm going to modify the bottom drain on the radiator so that it'll accept an M14 x 1.5 thread and I'm going to fit a Vauxhall Omega thermostatic switch, closing at 95 degrees and re-opening at 90... should be about right...

I'm also going to rip off the water-pump and check to see if it still has any vanes... at 170,000 miles, anything may have happened...

I'm also suspicious that the car may be running lean on LPG... It'll cost me money to check this out, but so will a new engine... If nothing else shows up, I'll get the LPG mixture checked... There is a Landi-Renzo dealer in Glasgow, but They charge main agent prices, so I use a trusted installed instead. He completely checked out and set up the system last year and charged me £50 for about 3 hours work... Most Installers can read diagnostics from more than one LPG system... It can't hurt to ask about....

The throttle-body tip is straight out of the USA version haynes manual... worth it's weight in Monkey nuts! They say to repeat about every 60,000 miles or sooner if lots of short, cold trips... Who are we to argue?

With regard to preferred LPG fits for Previa... I've had good reports of the OMVL millenium system... My bus has a Landi-Renzo system with OMVL vaporizer. I was thinking of getting an LR-vaporizer and recommissioning the system, but I may actually buy an OMVL system and ditch the L-R components... Who knows which is the better solution?

Best of luck with your L-R system...

Jeff

[Mick24]

I've seen quite a few water pump impellers corroded away - usually happens when the cooling system is run on anti-freeze/water mix instead of Toyota Forlife.

Happens on the higher mileage vehicles and shows up on fast A roads/motorways,due to the lack of flow caused by the corroded impellers.

[toyota.ie]

Check the rad and see if it has core has copper pipes if so the copper corrodes and blocks the internal flow of the coolant, which in turn overheats the vehicle another problem it could be combustion gasses leaking into the system (head gasket failure) you are putting yourself in for a lot of expense in my opinion you are not fully examining the problem. The vehicle originally was designed to keep itself cool without the mod. The thermostat had the centre removed, your problem has to be circulation problems maybe due to a blocked rad, water pump impeller worn or the head gasket.

[toyota.ie]

Check the rad and see if it has core has copper pipes if so the copper corrodes and blocks the internal flow of the coolant, which in turn overheats the vehicle another problem it could be combustion gasses leaking into the system (head gasket failure) you are putting yourself in for a lot of expense in my opinion you are not fully examining the problem. The vehicle originally was designed to keep itself cool without the mod. The thermostat had the centre removed, your problem has to be circulation problems maybe due to a blocked rad, water pump impeller worn or the head gasket.

[damesters]

Dear All

Since I took ownership of a '91 2.4 GL Previa last July, it's always had some "issues" with it's cooling system...

I noticed soon after buying it that long (over 100 miles), fast (80 mph +) motorway journeys would see the temperature guage souring skywards... :ffs:

A short break would soon have the situation under control and I must say that the threat of an overheating engine has done wonders for my driving license and fuel economy...

However, the problem has persisted and worsened... we've now got a situation where the car overheats on fast or slow journeys and we can only get it under control by turning the cabin heater on...  That's warm work in June! 

I've decided to "grasp the nettle" and I'm going to sort this problem out once and for all... here's a precis of what I've done so far, followed by what I intend to do... I'll ask some questions at the end, so listen closely now.. B)

First thing was to drain/flush/refill coolant - coldn't get the block drain plug out, so flush wasn't as complete as it could have been... Made no difference anyway..

Next, I considered replacing the thermostat... except the engine runs perfectly most of the time, with the guage needle bang in the middle... when I got underneath to check the 'stat housing, there are two new bolts and signs of instant gasket... I surmised that the previous owner had had this same problem and beat me to the thermostat, so I left it alone...

Next I tried a new (pattern) filler cap... no change

Now, after some investigation on t'internet,  :bookworm: I've checked out the viscous coupling, which appears to be cream-crackered... I can't detect any difference in the fan's resistance to me spinning it when the engine is stone cold, or immediately after an overheating incident...  It always seems very "loose" and must be slipping like a B*****D!!

I priced the coupling up at Toymota and wasn't suprised that it's £157 +VAT...

I know some folk who have removed & serviced these couplings (seized valve freed off and even refilling the silicon fluid - I wouldn't know where to look for silicon fluid... Is this something girlies get for "top-ups" after a boob job?  )

Anyhow... replacing or repairing the coupling would only have the cooling system back to 1991 standards and I would like to improve that situation...

I e-mailed Kenlowe, but they never bothered to e-mail me back... I reckon they could tell by the e-mail that I wasn't about tp part with nearly £200 for a Kenlowe kit... They were right!

So I've bought a nice new 15" electric cooling fan and mount (to fig an MG apparently, so I'll end up with a Previa "Sport") via Ebay and I'm planning to modify the Previa system to run with this...

What I need to know now is:

"What temperature the fan should be set to switch on at?"

Incidentally...

I was planning to remove the water pump to inspect the pump vanes (167,000 miles, so the pump may actually be worn out  ) While I'm doing that, I was going to have the thermostat housing machined to accept a thermal switch for the new fan... but without a guide to the temperature range, I don't know which donor car/switch to go for...

Anyone else have any clues?

Other imminent plans include: removal of viscous coupled fan and insertion of shorter pulley bolts... modification of OEM fan shroud to accept/mount MG fan and bracketry, removal and full flushing of radiator, filler tank and pipework (I'll get that darn block drain out this time too!)

I'm also planning to install a "manual override" switch for the electric fan... just incase the MG fan hasn't got the CFM capacity that the Previa needs...

I would love to hear from anyone who has modded their Previa/Estima/Lucida/Whatever to run an electric fan... I understand that the conversion also releases more mpg, so there's snother reason to go this way...

Anyone got any hints or suggestions..? :hokus-pokus:

←

[damesters]

Dear All

Since I took ownership of a '91 2.4 GL Previa last July, it's always had some "issues" with it's cooling system...

I noticed soon after buying it that long (over 100 miles), fast (80 mph +) motorway journeys would see the temperature guage souring skywards... :ffs:

A short break would soon have the situation under control and I must say that the threat of an overheating engine has done wonders for my driving license and fuel economy...

However, the problem has persisted and worsened... we've now got a situation where the car overheats on fast or slow journeys and we can only get it under control by turning the cabin heater on...  That's warm work in June! 

I've decided to "grasp the nettle" and I'm going to sort this problem out once and for all... here's a precis of what I've done so far, followed by what I intend to do... I'll ask some questions at the end, so listen closely now.. B)

First thing was to drain/flush/refill coolant - coldn't get the block drain plug out, so flush wasn't as complete as it could have been... Made no difference anyway..

Next, I considered replacing the thermostat... except the engine runs perfectly most of the time, with the guage needle bang in the middle... when I got underneath to check the 'stat housing, there are two new bolts and signs of instant gasket... I surmised that the previous owner had had this same problem and beat me to the thermostat, so I left it alone...

Next I tried a new (pattern) filler cap... no change

Now, after some investigation on t'internet,  :bookworm: I've checked out the viscous coupling, which appears to be cream-crackered... I can't detect any difference in the fan's resistance to me spinning it when the engine is stone cold, or immediately after an overheating incident...  It always seems very "loose" and must be slipping like a B*****D!!

I priced the coupling up at Toymota and wasn't suprised that it's £157 +VAT...

I know some folk who have removed & serviced these couplings (seized valve freed off and even refilling the silicon fluid - I wouldn't know where to look for silicon fluid... Is this something girlies get for "top-ups" after a boob job?  )

Anyhow... replacing or repairing the coupling would only have the cooling system back to 1991 standards and I would like to improve that situation...

I e-mailed Kenlowe, but they never bothered to e-mail me back... I reckon they could tell by the e-mail that I wasn't about tp part with nearly £200 for a Kenlowe kit... They were right!

So I've bought a nice new 15" electric cooling fan and mount (to fig an MG apparently, so I'll end up with a Previa "Sport") via Ebay and I'm planning to modify the Previa system to run with this...

What I need to know now is:

"What temperature the fan should be set to switch on at?"

Incidentally...

I was planning to remove the water pump to inspect the pump vanes (167,000 miles, so the pump may actually be worn out  ) While I'm doing that, I was going to have the thermostat housing machined to accept a thermal switch for the new fan... but without a guide to the temperature range, I don't know which donor car/switch to go for...

Anyone else have any clues?

Other imminent plans include: removal of viscous coupled fan and insertion of shorter pulley bolts... modification of OEM fan shroud to accept/mount MG fan and bracketry, removal and full flushing of radiator, filler tank and pipework (I'll get that darn block drain out this time too!)

I'm also planning to install a "manual override" switch for the electric fan... just incase the MG fan hasn't got the CFM capacity that the Previa needs...

I would love to hear from anyone who has modded their Previa/Estima/Lucida/Whatever to run an electric fan... I understand that the conversion also releases more mpg, so there's snother reason to go this way...

Anyone got any hints or suggestions..? :hokus-pokus:

←

did you replace the water pump? I am trying to figure out how to remove my water pump from my 91 preiva LE. I can't get it past the oil filter pump...any suggestions? Thanks

[PREVIACAR1]

Dear All

Since I took ownership of a '91 2.4 GL Previa last July, it's always had some "issues" with it's cooling system...

I noticed soon after buying it that long (over 100 miles), fast (80 mph +) motorway journeys would see the temperature guage souring skywards... :ffs:

A short break would soon have the situation under control and I must say that the threat of an overheating engine has done wonders for my driving license and fuel economy...

However, the problem has persisted and worsened... we've now got a situation where the car overheats on fast or slow journeys and we can only get it under control by turning the cabin heater on...  That's warm work in June! 

I've decided to "grasp the nettle" and I'm going to sort this problem out once and for all... here's a precis of what I've done so far, followed by what I intend to do... I'll ask some questions at the end, so listen closely now.. B)

First thing was to drain/flush/refill coolant - coldn't get the block drain plug out, so flush wasn't as complete as it could have been... Made no difference anyway..

Next, I considered replacing the thermostat... except the engine runs perfectly most of the time, with the guage needle bang in the middle... when I got underneath to check the 'stat housing, there are two new bolts and signs of instant gasket... I surmised that the previous owner had had this same problem and beat me to the thermostat, so I left it alone...

Next I tried a new (pattern) filler cap... no change

Now, after some investigation on t'internet,  :bookworm: I've checked out the viscous coupling, which appears to be cream-crackered... I can't detect any difference in the fan's resistance to me spinning it when the engine is stone cold, or immediately after an overheating incident...  It always seems very "loose" and must be slipping like a B*****D!!

I priced the coupling up at Toymota and wasn't suprised that it's £157 +VAT...

I know some folk who have removed & serviced these couplings (seized valve freed off and even refilling the silicon fluid - I wouldn't know where to look for silicon fluid... Is this something girlies get for "top-ups" after a boob job?  )

Anyhow... replacing or repairing the coupling would only have the cooling system back to 1991 standards and I would like to improve that situation...

I e-mailed Kenlowe, but they never bothered to e-mail me back... I reckon they could tell by the e-mail that I wasn't about tp part with nearly £200 for a Kenlowe kit... They were right!

So I've bought a nice new 15" electric cooling fan and mount (to fig an MG apparently, so I'll end up with a Previa "Sport") via Ebay and I'm planning to modify the Previa system to run with this...

What I need to know now is:

"What temperature the fan should be set to switch on at?"

Incidentally...

I was planning to remove the water pump to inspect the pump vanes (167,000 miles, so the pump may actually be worn out  ) While I'm doing that, I was going to have the thermostat housing machined to accept a thermal switch for the new fan... but without a guide to the temperature range, I don't know which donor car/switch to go for...

Anyone else have any clues?

Other imminent plans include: removal of viscous coupled fan and insertion of shorter pulley bolts... modification of OEM fan shroud to accept/mount MG fan and bracketry, removal and full flushing of radiator, filler tank and pipework (I'll get that darn block drain out this time too!)

I'm also planning to install a "manual override" switch for the electric fan... just incase the MG fan hasn't got the CFM capacity that the Previa needs...

I would love to hear from anyone who has modded their Previa/Estima/Lucida/Whatever to run an electric fan... I understand that the conversion also releases more mpg, so there's snother reason to go this way...

ID GO FOR THE RADIATOR MY GX HAS DONE NORTH OF 250,000 MILES ONLY THING I'VE CHANGED REALLY IS RAD IT WENT PEARSHAPED BACK IN THE SUMMER,COST UNDER A £100 VERY SIMPLETO FIT.IF WATER PUMP AINT LEAKIN (VISABLE LEAKS WILL BE SEEN AND IT WILL LOOSE WATER) IT'S LIKELY OK.

WILL WATCH FOR FURTHER POSTS GOOD LUCK GARETH.

P.S. GOT MY RAD IN ILFORD LANE ILFORD ESSEX

Anyone got any hints or suggestions..? :hokus-pokus:

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