Cooling Problems

Howdy Gents,
I think I've got a slow coolant leak (that I consider SOP) and it hasn't been a problem for the past few months since I bought my Landy. I had a long trip (~500 miles) on Saturday and the temp gauge started creeping up gradually during the trip, but nothing too worrisome. Knowing about the leak, I thought I'd top up this morning and be on my way.

So, being a good boy, I read the owners manual and my interpretation of the instructions was to add fresh coolant into the overflow reservoir adjacent to the radiator. The level was a tad low, so I topped it up (to half-full).

On the way into town the temp gauge went even higher - almost into the red. I got to a stopping point, let it cool down, slowly opened the reservoir (to vent pressure) and then opened the radiator with the expectation of just adding some coolant directly into it. To my surprise, coolant flowed up and out of the radiator.

Now, at the time the engine was definitely still hot, so I just now went out and checked it again. It's not 100% cold, but almost there and the coolant level inside the radiator is still right at the very top.

So, question: what should I be looking for to find the cause of over heating? (If it matters, I've got an '87 110 v8.)

Also, just checked that the fan is spinning with the engine running... it is.

does it overheat when idling or only when under load?

Both, I think. Although I haven't sat around idling long enough for it to get quite as hot as it does when rolling along. And when moving I'm not pulling anything or put anything heavy in it or going up major hills - just gently rolling along a flat road at 45 will get it all hot and bothered.

In all cases the temp indicator is *much* higher than it was a few days ago.

Hey Chris , Do both top and bottom rad hoses get hot ? , could be your thermostat sticking ? or your fuel mixture has leaned itself off , could be a couple of other things too ....

Ah, OK. I checked the top rad hose (it was warm), but not the bottom. If the bottom is cool, does that hint at a thermostat problem? Please tell me I don't have to drain all the coolant in order to replace the thermostat. (From the workshop manual diagrams it seems like that's not necessary, but I don't want to crack open the housing and have anti-freeze gushing everywhere...)

Got home from work and went back to the Landy...

From a cold start, idling easily, the temp shot up (see first pic) to where it was yesterday when I was driving.

Once it got hot, I stopped the engine, waited a few more minutes (to go get the camera...), and then checked both top & bottom radiator hoses.

Top hose was definitely warm, bottom hose was stone cold.

My layman's interpretation is that there's a blockage in the radiator. Could that also mean the thermostat is broken?

Speaking of the thermostat... where is the thermostat housing? The workshop manual has diagrams of how to fit and test one, but not where it's located. There's a yellow arrow in the second pic... is that it? If so, it sure looks like I'll have to drain the coolant to change the thermostat.

Thats it Chris , you will have to drain some coolant out first ( Do it when its COLD tho ) , find a clean bucket to catch your expencive anti-freeze in .

a nice new gasket wouldnt go amiss too ( cereal box and hylomar works a treat too ) , either just chuck a new thermostat in it or run without for the time being , yeah it'll over cool but at least you wont boil it .

If its still getting too hot after , then you have other probs with her .

OK, I'll give that a go tomorrow when the light's back. Now, where's my bucket...

Had a go before work this morning...

Workshop manual said to undo the rad plug to drain - looked easy. Plan was to pop the plug, drain to bucket, & remove thermostat. Except there was no plug. In that case manual says to remove lower hose. Then, instead of coolant -> bucket I get coolant -> chassis -> bucket. I doubt the engine would appreciate the mud... That means I need more antifreeze... ah well, off to work.

I removed the thermostat, re-filled the radiator with water and cranked up the engine, but it still overheats (at least while idling). Interestingly, the bottom radiator hose was noticeably warmer this time, but the engine gets just as hot (nearly in the red) just as fast (~5 min @ idle).

Any ideas what else I can check?

is your expansion tank cap working properly? it needs to hold pressure so the water dont boil. OR if its overpressurised check for hgf symptoms

I didn't notice steam or other venting (and I was looking carefully) at the cap or anywhere else in the engine bay. Upon inspection, the expansion tank cap looks normal to me: rubber ring in good condition and it was securely tightened.

One obvious problem: the engine oil level was a bit low. :doh: So I topped that up and will try again...

Also, before I started any of my faffing, I noticed some coolant on top of the engine -- near what I later learned was the thermostat housing. The thermostat housing gasket doesn't seem to be leaking, but there's another (triangular) plate that I've seen wet before -- see pic.

If the thermostat was broken then it might've made sense that a blockage there could've caused enough pressure to leak. Maybe there's a blockage somewhere further into the radiator. Then again, this morning the bottom rad house was warm...

A quick search of the interwebs for head gasket failure symptoms turned up one: check oil filler cap and dip stick for white-ish gooey residue -- there was none. Any other checks?

Just re-checked fluid levels: oil is back up to where it should be and so is coolant. Thermostat is removed, but engine is still overheating.

I'll check the workshop manual for suggestions, but this one might be a job for the garage.

Just a quick question, When the temp is on the hot can you still touch the heater hoses or is the temp of the hose to hot to touch? only asked as pos faulty temp gauge

Alright, finally had a free day to play with the Landy.

Talker - when I last cranked it, the heater hoses (there are two, AFACT) got warm. However, they're wrapped in a foam padding which is what I touched. Definitely too hot to touch the bare metal.

This morning I flushed the rad and engine cooling jacket. Not surprisingly it all seemed to flow freely. So, now the lead candidate is the cooling pump -- but how do I get the bloomin' thing off?

I'm trying to get the fan and rad shroud off to get at the pump. The shroud can be loosened from the rad, but not removed from the engine bay b/c there's not enough clearance between the rad & fan. So, my plan was to disconnect the fan from the pump and then pull out the shroud and fan together to get at the pump.

For starters, I'm not sure what I should loosen. I must be stupid b/c AFACT the workshop manual just says "remove the fan." There are four bolts on the fan and an enormous nut at the center. If I torque any of them the whole assembly spins. Don't think I've got the muscle to hold it still with one wrench and torque with the other.

What should I try?

Could I be in need of a something like this special tool?

Viscous Fan Hub Tool 32 & 36mm - 4x4 Store

I guess that means I ought to be going after the big nut at the hub. Now how to keep it from spinning...

them fan nuts can be a pig to get off , and some are LH thread just to confuse matters . what I used to do is shove a punch/open end of a spanner into that hole on the fan pully to hold it when you undo the centre nut .

sypher said:

them fan nuts can be a pig to get off , and some are LH thread just to confuse matters . what I used to do is shove a punch/open end of a spanner into that hole on the fan pully to hold it when you undo the centre nut .

Click to expand...

ye fans are a pain to remove. another way is this... remove the four 10mm bolts holding the fan to the visco clutch and slide the fan toward the engine. you can then use an adjustable to loosen the fan nut. fan and visco clutch will now be removed. the fan nut undose the same way it rotates. to stop the pulley from turning whilst you working on the fan nut use a long screwdriver wedged between the pully nuts.