Jump to content

3,9 V8 overheats when idling


stobbie

Recommended Posts

Belt is routed properly.

CO etc is perfect, no rich running on our gas analyzer.

System is pressurised, no leaks, no steam/bubbles

Using the standard 3,9 14cux ecu of the disco

I don't think there still is an airlock.

No knock sensors, ignition timing spot on

The thermostat has only one valve. I think only the TDI's and the 4.6 have a thermostat with the extra valve?

At this moment I'm removing the waterpump of a 3,9 Disco to try that one. That car has no cooling problems, so the waterpump should be ok.

Link to comment
Share on other sites

Tdi rads are about the same size as SIII rads, and SIII conversions using the original rad often struggle with heat. I think that rad is your problem, in all honesty. I'd recommend using the V8 rad.

Really I have been running a V8 Series 1 on a Series Diesil rad for over 30 years and its never overheated, it is not a Series 111 rad and I am thinking of replacing it with one. Is your comment specific in S111 having problems due to the car type rad or Series in general?

Marc.

Link to comment
Share on other sites

I have noticed that the TDC mark on the pulley is two degrees out, I've advanced the timing a little more and have set it 8 BTC now. It heats up a little slower, and when I drive the car the temp sits in the middel of the gauge, but when left idling it slowly creeps up again and keeps climbing. After ten minutes it hits the red mark. It's then 102 at the top hose and only 15 degrees cooler at the bottom of the rad.

ibf75t.jpg

Link to comment
Share on other sites

Does sound like flow is your issue.

One other thing, did the thermostat have a jiggle pin in it, and did you mount it at the top? (Assuming it is in the inlet manifold).

Failure to do so can lead to you never really bleeding the system properly and the thermostat not ever opening.

Be good to know your hose routing for the heater, could have some bearing on things...

Link to comment
Share on other sites

Having been through something similar myself, I can say that nothing will affect a V8's cooling like the radiator. I fooled with all sorts of things - timing, mixture, vents - until I swapped rads, which did the trick.

Link to comment
Share on other sites

Really I have been running a V8 Series 1 on a Series Diesil rad for over 30 years and its never overheated, it is not a Series 111 rad and I am thinking of replacing it with one. Is your comment specific in S111 having problems due to the car type rad or Series in general?

Marc.

SII/SIII with V8, not with 2.25s or Tdis. It's certainly not guaranteed to be an issue, but it is the engine that has the most trouble with Series rads. That being said, it could be because the owners used tired rads, lower thermal capacity versions (three row), or didn't have an appropriate fan, but I have come across far fewer cries for help from those with four pots.

Link to comment
Share on other sites

Only now I saw what you meant...

- it looks like two different cores stuck together - the lateral pipes don't match up either side of the vertical joint, and that may be causing a big restriction.

You can see the aircon condensor in front of the rad, that's why it doesn't line up :D

Link to comment
Share on other sites

My v8 runs on a TD rad. The rad is fine but your rad may not be, has it been flushed atall?

You have already addressed retarded timing, the only thing I would say about that is you shouldnt nessasarly beleve the timing mark lies, Mine is 8-10° out which I could only figure out with a piston stop So you could find yourself advancing it further

Your fan is on the correct side of the radiator?

Link to comment
Share on other sites

Doug makes a good point, not as daft as it sounds - when I did my Tdi retrofit, I had to use an electric fan. I ordered a "puller" to sit behind the rad. The fan arrived in a box labelled "puller", and the instructions stated it was a puller. I did notice that the camber on the blades was the wrong way around, so I flipped the rotor over and fit the unit. The first time the engine had to work hard, it nearly overheated - it was a pusher and was trying to blow against the ram flow from vehicle motion, reducing rather than increasing rad airflow. Swapping the polarity of the two wires tot he fan motor solved all the problems.

So, just because the fans are labelled as pusher or puller, it doesn't mean they are as claimed - check the airflow from each yourself!

Link to comment
Share on other sites

We have checked the airflow, and it pulls.

Ofcourse there is an aircon condensor in front of the rad and an automatic gearbox cooler as well. So that restricts airflow a bit and heats up the air already.

But I have no other options. I cannot fit bigger fans, there is no space and I cannot move the other coolers.

Link to comment
Share on other sites

The thermostat has two valves in it. One opens flow to the radiator and the other closes off the bypass flow. If you remove the thermostat, then the bypass flow does not get shut off and the flow will not be forced through the radiator.

Not on this. You are thinking about later models. This 3.9 will have the thermostat in the housing located on the inlet manifold.

Stobbie - do you have an independent gauge fitted where you can read actual water temperature ? Is the fan switching on at the correct temperature ? A thought, was that the sender unit located in your top hose might be causing an issue for some strange reason :blink::blink: . We generally fit the the fan sender where you currently have your air con fan switch (we remove air con).

Are all 8 cylinders firing ?

With thermostat removed have you tried blanking the pipes to your heater matrix (basically no bypass, so all water has to go through the rad) ?

How clean is the rad inside ?

Gordon

Link to comment
Share on other sites

Rad is new.

Yes, we have checked the watertemp,and it goes up tot 101 .

With the visco, but without a shroud it acted the same.

Our customer needs aircon.

All cilinders are firing.

We have removed the valve in the thermostat, this has helped a little, but at idle it still creeps up. Ofcourse it takes a little longer now because it starts a lower temp.

We have fitted a fan switch that turns on at 90 and shuts off at 80. That is to low, but we thought it might help a bit with cooling, but it doesn't.

We haven't blocked the heater hoses to check, but we have made sure there are no airlocks in the heater and the heater stays very very hot. Doesn't help with cooling if i put it on at max.

Link to comment
Share on other sites

Just got back after a whole day in the car, so haven't worked on the V8 myself today...

But our mechanic has fitted another new 19J radiator and tried to fit another water pump, but we did not have any gaskets in stock.. Hopefully tomorrow again.

Top hose is 102 degrees, bottom hose is 87 degrees.

I'll try to sketch a drwaing of the system tomorrow.

Link to comment
Share on other sites

So I ran a 3.9v8 in my Defender with a twin electric fans with no problem with over heating at idle or under competition conditions (high load, very low speed) (except when I filled the fins with lots of Mud)
It use ESR76 which is a 90/110 HD Petrol/Diesel/V8 rad.
It was a manual with no aircon but it also has an oil to water doughnut cooler.

One thing I note is that the Rad look to be Aluminium, cooper material has better heat properties But you can construct more efficient designs in aluminium, so overall there can be no difference on well designed and constructed Rads.

have you removed all the hoses and checked for de-lamination as that can block the flow of water.

Other possible solutions
Some people have mounted cheap I think Mondeo single electric fans to Landrover Rad, may be you can add a pusher fan to help the normally puller fans.
or

A lot of heat is radiated by the engine and exhaust in to the engine bay some say that removing the rear bonnet seal helps hot air escape.
or
Put less heat in the engine bay by having the manifolds ceramic coated (expensive I believe)
or
add a bonnet fan http://www.kenlowe.com/Ventilation.php (but can spoil the look)
or
Cut holes in bonnet edge at rear or louvres (I think HFH did these to help solve his cooling problem) (but can spoil the look)

I noticed the thread is similar to http://forums.lr4x4.com/index.php?showtopic=56553

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy