Overheating 1HDT

[albycamel]

I've done a lot of searching on 1H8MUD and the general interweb. My 80 temperature gauge rises whenever I start to drive up a hill and then falls after the incline. It rises above half - to about 3/4, but never close to the red - but I appreciate it takes a large temperature difference for the factory gauge to move, so it isn't healthy.

When this first showed, it was before a planned timing belt change, so I just replaced the radiator (quality allloy), thermostat (OEM), water pump (OEM), and fan clutch (asin), and flushed out the engine, assuming this would cure all. There is no sign of head gasket issues, no bubbles in the overflow, no coolant use, etc. - although I appreciate that a head gasket is still possible. There was quite a lot of crud when I flushed out the old radiator, so I am going to remove the thermostat and try flush again, assuming there might be some sort of blockage that I have missed.

Grateful for any advice on how best to flush or anything tips I can try before turning my focus to the head (my plan is to jam a garden hose into the outlet (having removed the thermostat from the inlet). I do have an aftermarket temp and pressure gauge on order, but that wont resolve the overheating issue.

Many thanks, and apologies for another overheating post.

 

[Jon Wildsmith]

How long have you had it? Has it always done this or is a recent thing? Asking how long you owned it in case a previous owner has done the temperature gauge modification that takes away the dead zone and means the needle does move up a bit when the engine is under load.

 

[albycamel]

How long have you had it? Has it always done this or is a recent thing? Asking how long you owned it in case a previous owner has done the temperature gauge modification that takes away the dead zone and means the needle does move up a bit when the engine is under load.

Thanks Jon, I have owned it for years, but has only recently become a problem - (I say recently, but it has been ongoing for over a year now, and I really only drive it occasionally when I have a new idea of troubleshooting the overheating issue - I originally hoped it might just be air in the system and a long drive did seem to stabilize the gauge, but the next few drives it seemed to get worse).

 

[Lorin]

I wouldn’t assume you’ve got a problem that needs fixing until you’ve checked and verified what the temperature is doing.

My suggestion would be to fit an aftermarket coolant temp gauge. Drive for a bit and get some good data on your temps. That’ll tell you if have a problem that needs looking into. It could well be fine and even if not, you’ve now got an accurate way to keep monitoring.

 

[Ben Stratford]

Does it run just as well as before?

I would look at the easy things first - like Lorin says, check the gauge.

Failing that…

Not all head gasket failures involve water and oil mixing, two adjacent cylinders may be leaking compression into each other which a compression test would find out. Not sure if this is relevant to your engine though.

 

[albycamel]

I wouldn’t assume you’ve got a problem that needs fixing until you’ve checked and verified what the temperature is doing.

My suggestion would be to fit an aftermarket coolant temp gauge. Drive for a bit and get some good data on your temps. That’ll tell you if have a problem that needs looking into. It could well be fine and even if not, you’ve now got an accurate way to keep monitoring.

Great advice and certainly working toward that. But it really does run hotter than it used too and comparing the radiator and hoses by feel to my 1HDFT - noticeably hotter. Hardly scientific or good data!

 

[Dave]

Are you sure the original radiator wasn’t clogged up, and the new aftermarket ome just isn’t up to the job?

 

[albycamel]

Are you sure the original radiator wasn’t clogged up, and the new aftermarket ome just isn’t up to the job?

I can't be sure, but it is a Terrain Tamer Heavy Duty alloy radiator, so I would hope it is at least as good as OEM. It replaced a Nissen radiator.