Overheating engine - some help?

gbremset

So.. I thought I'd try this here, as I'm not too keen on putting the car into a garage. the car is reaching it's end of life, and I'm only weeks away from replacing it.
However, I can not afford to replace it now, and I need the car to get to and from work.

The issue is with overheating, and it has developed as follows:

Originally, the car would overheat, only when I was driving on motorways for a prolonged amount of time. (About the distance from the drogheda/balbriggan exit of the M1 and down to swords (passing 2 exits on the way)
This has now been gradually shortened, and now I can't even drive from swords to balbriggan on the old N1 without reaching unnecessary high temparatures.
No matter how hot the engine is, the heater hardly gives off any heat at all.
Another strange thing, is that very often when the engine is between 50 and 80% on the temp meter, and I hit something like a roundabout or similar, it goes down clearly, giving me the impression that it's something to do with the revs of the engine, but if I try to drive in a lower gear, it makes no change, even though the revs are higher.

There are no leaks in the water system, and when idling, the fan goes on and off like I'd expect it to.

I consider myself fairly technical, and most of the time, if I know what is wrong, I can fix it myself. It's the "figuring out" part I'm having trouble with.

Here's what I've tried and tested until now:

1. New thermostat - Made no change whatsoever
2. Cleaning the cooling system with a cleaning fluid, tried once - No change (If nothing, it may have made it worse. :P )
3. Testing circulation. This was done by removing the return hose from the engine to the top of the radiator, and squeezing the inlet hose at the bottom of the radiator. Water clearly moves and comes out of the output nozzle on the engine.
4. Testing the radiator for blockages. Done by opening the draining cap on the bottom of the radiator, emptying the whole system completely, and then pouring water in to the radiator. Water does not instantly come out of the draining cap, but as far as I understand, some delay is expected. We're talking 5-10 seconds from starting to pour, until the water starts running out of the draining cap.

The car is a 1993 Mitsubishi Lancer 1.6 GLXi, 16 valve with 127k miles on the clock. Timing belt and water pump was changed at around 105k.

The problem initially appeared while I was working for WRC: Rally Ireland, when it overheated and boiled heavily and I didn't notice until it stopped by itself. (Due to the darkness, I couldn't see the smoke coming out from the right side of the bonnet)
At the time, I could drive about 20 minutes, before I had to stop, let the engine cool down for 15-20 minutes and then drive another 20.

so.. that's my story.. Any questions, or tips.. Something you want me to go out and check?

All I need is a quick fix, so I can get the car to last me for 3 more weeks or so. As it stands today, with the problem getting worse and worse (yesterday I had to stop 3 times on the road from swords to balbriggan, with the car having been unused from 7.30 am to 4pm).

mike65

There must be an internal leak (connected to the initial overcooking on rally duty).

Mike

gbremset

Well.. I'm not seeing any loss of water at all, the oil is crisp and clear (Dipstick), and there's no other obvious signs of oil or water in any parts of the engine other than where it should be. (No white oil or oil in water, and no excessive smoke from the exhaust)

ART6

From your description it seems that there is no coolant circulation through the engine, as you have obviously worked out for yourself going by the checks you have tried. Certainly the fact that you can run for 20 minutes before it overheats, and no heat from the heater proves that. Generally, I would suspect either the water pump impeller loose or a jammed thermostat, but you have changed the latter. The fact that the water pump was changed fairly recently doesn't mean it can't be faulty now, of course, so I would still suspect that since the condition has become worse over time.

The other possibility is that the system is airlocked -- some cars are a bit prone to that, and boiling the coolant just makes that worse. One thing that might work if that's the case is to run the engine on idle with the rad or expansion tank filler cap off. That has worked for me once or twice, but put a rag over it so you don't get a sudden spray of hot coolant!!

barthek

you sure water pump is fine?

how do you know the engine is actually overheating? maybe its only a sensor issue ?

woop

he said there was boiling water

make sure youre belts are tensioned

and you are sure youre not losing coolant??
possibly an air lock/block in the heater matrix as its the highest point in the car aswell as another problem

barthek

woop wrote: »

he said there was boiling water

make sure youre belts are tensioned

and you are sure youre not losing coolant??

to be precise - he didn't say the water is boiling now. he did say that it had happened before though.

OP, would both hoses from the rad get warm or only one of them?
i mean - significantly warm

masseyno9

I would second the airlocked thing. There is no circulation of coolant if the inside heater isn't working.

The heater takes air that flows over the hot pipes and blows it into the car. if this air is cold, then obviously these pipes are not getting hot (i.e. removing heat from the engine).

An airlock is one possible explanation, and there may be more, but try bleeding your coolant system. Usually involves opening bleed valves, one near the radiator and one near where the coolant lines enter the block. You need to open these, and fill the coolant bottle, rev it a bit, close them. Something like that. Maybe better to google how to do it!!

gbremset

woop wrote: »

he said there was boiling water

make sure youre belts are tensioned

and you are sure youre not losing coolant??
possibly an air lock/block in the heater matrix as its the highest point in the car aswell as another problem

Yes there is still boiling water.. Nice bubbly sound from the radiator when I stopped outside the house yesterday. I emptied the water system and refilled it with fresh water (I have no coolant added, but as far as I understand, that wouldn't make the car behave like this)

when I emptied it yesterday, it was still full to the top (that little edge at the top of the radiator, which I use as indicator that it's full), and I had been driving for about a week like that.

gbremset

ART6 wrote: »

From your description it seems that there is no coolant circulation through the engine, as you have obviously worked out for yourself going by the checks you have tried. Certainly the fact that you can run for 20 minutes before it overheats, and no heat from the heater proves that. Generally, I would suspect either the water pump impeller loose or a jammed thermostat, but you have changed the latter. The fact that the water pump was changed fairly recently doesn't mean it can't be faulty now, of course, so I would still suspect that since the condition has become worse over time.

The other possibility is that the system is airlocked -- some cars are a bit prone to that, and boiling the coolant just makes that worse. One thing that might work if that's the case is to run the engine on idle with the rad or expansion tank filler cap off. That has worked for me once or twice, but put a rag over it so you don't get a sudden spray of hot coolant!!

As the water pump is pretty difficult to remove on this car, it's hard for me to do any checks on it, but you can definitely be right about that. The airlock options also sounds quite logical, but the reason I didn't think of this in the first place, was that after I did the "circulation" check, by squeezing the bottom hose with the top hose off, there was obvious movement in the water that was left in the opening after removing the hose, ie. water spurting out when I squeezed hard enough.

I'll try to bleed the system when the weather clears to see if that changes anything..

woop

as said above are both hoses going to firewall equal in temp?
give the inlet a bit of a squeeze
but Id say youre airlocked at the thermostat aswell which is causing youre over heating-does the rad get hot?

gbremset

So.. i was just outside, located the bleeding point (on top of the thermostat housing, labelled with a "Do not open when hot" sticker), which was as high as I could see on the engine, with regards to anything related to water.

I removed the bolt, and the bottom of the bolt was dry.

I then removed the radiator cap, and water bubbled up the hole where the bolt had just been.

Next I removed the radiator bleeding plug, and the system drained.

What should I do next, just replace the bleeding point bolt, then the radiator plug and refill? Or do you want me to check something else while the weather is fine

JHMEG

Airlock in the heater matrix. Hot water rises so, so if the pump wasn't working you'd still get heat near the tops. I wouldn't rule out other airlocks either.

Andrewf20

Hmmm. Strange symptoms.

"Based on this: Originally, the car would overheat, only when I was driving on motorways for a prolonged amount of time."

Check the rad it not blocked at the front with leaves and debris etc, and that the viscous fan coupling is okay.

gbremset

Andrewf20 wrote: »

Hmmm. Strange symptoms.

"Based on this: Originally, the car would overheat, only when I was driving on motorways for a prolonged amount of time."

Check the rad it not blocked at the front with leaves and debris etc, and that the viscous fan coupling is okay.

Radiator is nice and clean.. That was the first thing I checked, but it was so obvious I didn't really bother to mention it. :P
The fan comes on and goes off when idling, when I'm driving I can't really hear it, but as it does when Idling, I expect it do do so when not as well. :P

gbremset

JHMEG wrote: »

Airlock in the heater matrix. Hot water rises so, so if the pump wasn't working you'd still get heat near the tops. I wouldn't rule out other airlocks either.

Gonna pop out and see if I can find any obvious connection to the heater here..

There's a hose going from the thermostat housing to the firewall, and one going from the firewall to the other side of the engine block, but no obvious bleeding points, and no sound of bubbles or any signs of water in them when I squeeze them after draining.

gbremset

After googling a little, here's the procedure I followed on how to bleed and refill the cooling system on a lancer with the 1.6l 16 valve engine:

1. remove the bleeding nut on top of the thermostat housing

2. Remove the radiator cap

3. Remove the bleeding plug on the bottom of the radiator

4. Allow the system to drain completely

5. Replace the bleeding plug on the radiator, but do not tighten it

6. Refill with coolant/water mixture until it bubbles out of the bleeding plug, and then tighten the bleeding plug.

7. Continue refilling until it flows evenly out of the bleeding plug on top of the thermostat housing, flowing evenly means that there's NO bubbles in the liquid that comes out.

8. Replace the Bleeding plug on top of the thermostat housing and tighten.

9. Start the engine, heater on full power and max heat

10. refill with water as the radiator level drains.

11. Leave idling until at normal operating temparature

12. The liquid will start flowing out the top of the radiator, let it do so until it starts bubbling and spurting (boiling), and replace the radiator cap.

13. Stop the engine and allow to cool, and refill with coolant as necessary.

When following that procedure, I noticed that both the top and bottom hose to/from the radiator get equally warm. (No-touch heat), but there is still no heat coming from the heater..