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wilbo666
Forums Junkie

Location:
Brisbane
Registered:
May 2002

Overheating	Tue, 03 December 2002 03:00

My car seems to overheat, even on the highway doing 110k / hr... Why? I have tried two different temperature senders, had the radiator properly rod cleaned, and have checked the thermostat. So now I'm confused!! What could it be? I recently did the rings and had the head reconditioned so I know the engine is healthy, however the previous head was VERY corroded and the radiator was also blocked (from the previous owners not using coolant), so the only thing I can think of that could be causing the problem is a corroded water pump?? Any other ideas? (Car is a 1981 MX62 Cressida 5M-E) Cheers Wilbo [Report message to a moderator]

GZE-STYLE
Regular

Location:
Camden
Registered:
July 2002

Re: Overheating	Tue, 03 December 2002 06:48

water pump? [Report message to a moderator]

5KinKP60
Regular

Location:
Finland
Registered:
June 2002

Re: Overheating	Tue, 03 December 2002 23:28

I had my VW to overheat the other day. Not enough coolant in the system, the flipping water partially froze over. Caused pretty apparent circulation problem. I take it this isn't one of your worries over there. --- Anyhow, get a pressure gauge (industrial supply hardware store should be able to cater this need, elaborate connections DIY way) that reads at least up to 2 bars. Pipe that in onto anywhere between wasser pumpen and thermostat. Good cooling system should run at about 1,5 to almost 2 bar pressure level. Maybe previous owner yanked that plastic cover away that used to be installed in between bottom of radiator and engine cross member. That is ever so important. It helps to maintain ever so slight underpressure area right behind cooling radiator - it helps air draught to walk right through the radiator. See if any plastic coverings are removed from either side of radiator. They have to be there. Otherwise air draught will walk right past/around the radiator since that route has less restrictions. This applied to all sides of radiator, top and bottom also. For reference have a look at engine bay of any modern car in a showroom - very well enclosed radiators you will see. No other way for air draught than go right through the radiator. Some have reported resorting into opening enginebay lid from windscreen side by few centimeters. This does generate a local low pressure area at back of enginebay, thus helping to extract air away and encouraging ventilation this way. My personal opinion is that such cars most likely have previously mentioned plastic OEM covers yanked away from enginebay frontal area, thus driving car into overheating problems in the first place. Normal OEM air circulation is as follows. Air draught rushing past car chassis creates previously mentioned low pressure area right behind radiator. This attracts some fresh air to engine bay htrough radiator. This slightly warmed up air is quickly sucked away by low pressure area lingering between engine and bottom of firewall - well actually between engine cross member and bottom of firewall. This phenomena can be enhanced further (to some extent) by bolting on that all so ever cruicial tuning apparel - front spoiler. This is why many cars (even way back in the -70's and -80's) had 'em installed at the factory already. It may not have been any more monumental than a mere 2 inch wide strip running from left to right - but it did the job. Bottom line is to restore cooling system to OEM condition and making sure of proper enginebay ventilation. (Corroded head water ducts/channels will lessen heat soak into water by fairly remarkable percentage. Have a look into this good people over there. Trapped air bubbles in the cylinder head may give problems at times. Have a look into different ways for making sure system is rid of air bubbles.) Comments welcome. -A. [Updated on: Tue, 03 December 2002 23:48] [Report message to a moderator]

mrshin
Forums Junkie

Location:
Montrose, VIC
Registered:
May 2002

Re: Overheating	Wed, 04 December 2002 00:45

A big arse reverse bonnet scoop to let the air out is not only practica, it looks damned tuff! the perfect excuse... Otherwise, be sure theres no blocked rad/block/hose/thermostat/etc., then pull out the water pump, you'll probably be greeted by a very nasty rusty mess... [Report message to a moderator]

wilbo666
Forums Junkie

Location:
Brisbane
Registered:
May 2002

Re: Overheating	Wed, 04 December 2002 06:13

Ok, the shroud that is meant to be underneath the car (Front to Crossmember) is NOT there, is this the answer to my overheating?? Also could the clutch fan be the problem?? Cheers Wilbo [Report message to a moderator]

justcallmefrank
Forums Junkie

I supported Toymods

Location:
Perth
Registered:
May 2002

Re: Overheating	Wed, 04 December 2002 06:42

I spoke to my mechanic when my car did the same thing. He said my clutch fan wasn't working great, but it wasn't the problem. To try and fix it, I flushed out the cooling system, replaced the coolant, had the radiator cleaned out, basically everything I can think of....no avail. Mechanic hooked up a gauge tester to it, gauge reading wrong [Report message to a moderator]

Pumpkin
Regular

Toymods Board Member

Location:
Sydney
Registered:
September 2002

Re: Overheating	Wed, 04 December 2002 21:15

You can feel the difference on the clutch fan.. Let your car warm up and you should be able to here the fan come on . Very similar to a normal electric fan. Also, see if there is any movement on the fan itself. [Report message to a moderator]

wilbo666
Forums Junkie

Location:
Brisbane
Registered:
May 2002

Re: Overheating	Fri, 06 December 2002 05:29

Ok, an update. Put in a new lower radiator hose (Genuine Toyota $11 how good is that!), and while I was there I pressure tested the system (maybe too much pressure) and I saw two tiny little jets coming out of the radiator, how much pressure is the system meant to have I thought only about 15psi so maybe I was putting too much pressure into it.... oops? However I then took the car for a drive with its new radiator hose and it still got "hot", fair enough it didn't go into the red or as high as usual but it was at about 3/4, do you guys consider that fine? Was a really hot day too though, about 35 degrees. Took the radiator cap off while it was still hot (carefully) and the system had heaps of pressure, so I guess that a good thing right? While it was off I can also vouch for the fact that both the thermostat and the water pump seem good (saw plenty of flow when I started the car). So is 3/4 on a hot day ok?? (and do I need to worry about those tiny holes in the radiator under high pressure although I can't see anything coming from then when driven / hot?) Cheers Wilbo [Report message to a moderator]

skitz_supra
Occasional Poster

Location:
North Brisbane
Registered:
May 2002

Re: Overheating	Fri, 06 December 2002 06:07

get the holes fix straight away, a leaking cooling system is a leaking cooling system, and isn't good at any temp/pressure. side note: my car has 15psi pressure in the radiator normally, not when pushing it. so yeah, get the rad fixed, then look into a thermo fan, should help heaps, especialy in start stop traffic. c-ya, [Report message to a moderator]

wilbo666
Forums Junkie

Location:
Brisbane
Registered:
May 2002

Re: Overheating	Fri, 06 December 2002 06:10

The holes were tiny and only at the highest pressure I could get into it.... still I guess I will need a re core, how much are one of those these days? Cheers Wilbo [Report message to a moderator]

Esteban
Regular

Location:
Brisbane - Chapel Hill
Registered:
June 2002

Re: Overheating	Sun, 08 December 2002 10:08

Small holes quickly become big holes when you apply heat and pressure ... [Report message to a moderator]

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