Selective overheating...

1999 Jimny 70K on the clock...

OK, when I bought this vehicle it overheated and went back to the garage. Apparently it had previously had a head gasket fitted but was bodged. The garage removed the head, sent it of to be re surfaced and then reassembled. They also fitted a new viscous fan, new stat and reverse flushed the block and rad. That then seemed to solve the problem.

Now this morning I took SWMBO to Tesco's (about an 8 mile journey), due to a Corsa sitting on my bumper I did raise the speed to about 75 and drove at this speed for a few minutes. It was then that I noticed the temp guage climbing. (It normally sits at half way). This was around a few minutes before we reached our destination. Whilst she was running hot she started to hold back (expected that really, and when we came to a stand still the revs dropped lots lower on tick over as normal to the point that the oil light was flickering).

Went and did our shopping (about an hour or so). Returned to the vehicle, stuck the heater to hot and drove home keeping the speed to under 55. No overheating or probs. Temp guage climbed to half way and stayed there...

I'm starting to think the rad is blocked. Now before I shell out £100 for a new one I thought I'd ask your opinions. I just HATE having an unreliable motor

Thanks in advance.

might be worth taking it out and giving it a clean yourself. i did that with mine as it heated up a bit too quicly for my liking. Also check the fins are not all bent over etc.

Cheers for that, I'll have a looksie.

Thermostat? Our Landcruiser did this, drove fine no probs, but when we had it loaded with a 2tonne trailer and pulling up a hill the temp gauge started to rise.Might be worth looking into.
Easy to test yourself anyway.

Second vote for the Rad .. when driving in low though sticky mud, ours overheats. The source of teh problem ... Rad full of silt and mud, plus lots of bent fins.

New rad has been sat in teh garage for the last 6 months waiting to be fitted... Summer Job I think !

Cheers guys, it's had two stats so I'm pretty sure it's not that. Will drain and pull out the rad, I have a feeling that the previous owner has used magic sealer in the past when the HG was bodged

yeah sounds like the rad, you never no if they have used something like that K seal you can get

Check the bottom hose. I noticed that mine has a kink flat in the middle, may be slightly too long. Never given me any trouble (yet) but it must restrict the flow.
I can't do anything about it with the water in.

Have drained the rad and noted what looks like copper particles, K seal?? Dumped a bottle of rad flush in and topped up with water. Stayed at normal temp (bonnet down), held revs at 2K and temp started to rise

Waiting for it to cool drain so I can drain it again and have a look at the water. Can hear gurgling sounds within the top hose. No mayonaisse under filler cap or on the dip stick.

Royal pain in the bum

Some fins are bent over on the rad but seeing as its getting too hot without driving I doubt now that that is the cause.

What do we reckon?

Thanks in advance

this might be an abvious question but does the fan go round. if it heats up when its just sitting generaly means theres no airflow over the radiator. if the rad is hot then there is water curculation.

if the radiator is not full of water then that could and will effect the cooling too.

let it cool down open the rad and fill it with water. run it without the lid off and keep topping it up for a minute or so.

Most likely the radiator is blocked inside and restricting water flow. I doubt if radflush will shift a blockage.

It will overheat standing if you rev it, it is not a Landrover, which is supposed to run whilst stationary.

Is the fan driving? it should be blowing a gale if the engine is overheating. When stationary, the viscous unit should show some resistance to turning the fan blades by hand.

Fan appears ok and it is definitely a new viscous unit. Will drag the rad out and reverse flush it. Cheers guys

From an empty rad to full it's taking slightly more than 2.5 litres if that helps