2.25 petrol overheating

[Jdnewberry]

I have been fighting an overheating problem and need some help from you guys.

I have a 3MB 2.25 petrol with 27,000 miles that over heats at highway speeds. The head has been shaved from 7:1 compression to 8:1 compression and converted to unleaded. The block has been flushed, it has a new 4-core radiator from Rovers North, new distributor, new plugs, new carb, etc... But it still overheats.

I have been over everything I can think of and I'm out of ideas. The curious part of the problem is the temp in the radiator. The coolant gets to about 210 deg after a short run at highway speeds and will be about 10 deg cooler at the bottom. The radiator is evenly warm from side to side, so it isn't blocked. The water pump is perfect, the thermostat works correctly, new radiator shroud, hoses are fine, the timing is set per specs, carb has the proper jets, but it still runs hot at speed. After a short drive at 35-40 mph, temp drops back down.

I'm lucky though. My mechanic specializes in classic European cars, graduated with honors from MIT, and loves to give free advice because it keeps his work load down.

He said something that confused me today. He said he thinks my radiator might be flowing to fast and not giving the coolant time to cool off. Is that possible? I've never heard of such a thing! If the coolant is spending less time in the radiator, wouldn't the time it's spending in the water jacket be proportionally less?

If the cooling system is not the issue, I'm out of ideas. I have run the timing everywhere from 12 deg BTDC to 6 deg ATDC, installed a new weber with new jets (165 main, 190 air corrector, 50 idle, 40 back bleed, 55 pump, F6 tube) gone 1 heat range cooler on the plugs and it still runs hot at speed. I have even changed the air corrector jet to 170 thinking that maybe it was running lean.

Any ideas on something I have missed? Is there any truth the radiator flowing too fast?

Thanks in advance.

[TravelinLight]

I cannot imagine a situation where the 2.25 with everything you have stated done would overheat.

Is the fan belt the correct one for your pulley and tight enough to spin as supposed to? The reason I ask is the issue that it is not circulating the fluid to be cooled properly? Is it slipping at higher RPMs.

Have you tried to run it without the thermostat to insure you are getting the proper flow? Even though it opens as expected I would run it without one for a trip or two to see if you can isolate?

[Jdnewberry]

The fan belt is tight and it is the correct 1050mm size. I know it's pumping at speed, because the temp in the radiator runs so high. I have not removed the thermostat yet, but since the the temp runs so high, I can't imagine it's restricting the flow.

I may try to run it without the thermostat tomorrow if the weather holds. It's been rainy here and my top is off!

[SafeAirOne]

Is your mixture too lean? Does it cool off if you enrich the mixture?

What temp rating is the installed thermostat?

[Jdnewberry]

I'm not sure about the mixture. I have asked about that, but I can't find anyone to test it for me. I do have the recommended jets for the 2.25 installed in the webber and have even gone down a size on the air corrector, but it didn't seem to make a difference.

I wonder though, because where the exhaust runs under the footwell, it'll roast your toes when your driving. I can't imagine that's normal.

The thermostat is the 74 deg and it opens early if anything. It seems to open about 70.

[darbsclt]

Silly question... but, you're sure that the thermostat installed is a "skirted" type.
I only ask because use of a non-skirted type, while appearing to function, won't channel the water properly for adequate cooling.

Cheers...

[Jdnewberry]

There's no such thing as a silly question. Yes, it is skirted. I picked it up from our hosts this spring when the weather warmed up.

[ignotus]

Where and how are you measuring the temp after running? So a 74 thermostat is equal to 165F, 100C=212F. Like darbsclt says make sure you have the correct stat ^^^^. Not sure but TeriAnn might have it on her website. http://www.expeditionlandrover.info/

[leafsprung]

A few things that would be helpful in diagnosis:

-an infrared thermometer would be helpful in determining your coolant temperature at various points in the system
-check your plug color for evidence of correct mixture (light brown ash)
-bubbles in coolant or coolant loss indicating a gasket failure or crack

[darbsclt]

I may try to run it without the thermostat tomorrow if the weather holds. It's been rainy here and my top is off!

Keep in mind... running the engine at temperature without a thermostat will simply cause the coolant to flow through the bypass port rather than the radiator (the 'stat skirt blocks this port when functioning properly). This can cause the engine to run hot.

As Ignotus referenced, Teriann has a nice write up HERE (http://www.expeditionlandrover.info/Thermostats.htm)

[lumpydog]

Does your gas gauge work?

I ask because, if it doesn't, it may be that your voltage stabilizer is not working and feeding your temp gauge and gas gauge the wrong voltage... and causing both to be inaccurate. It's harder to tell something's wrong with the temp gauge, but the gas gauge - it's more obvious if it's off. If the gas gauge is not accurate, try swapping out the stabilizer.

Also, consider the temp sender... Mine recently bonked. I noticed it when, within a minute of starting the engine, the gauge showed the engine as mid gauge on the temperature gauge... Does it warm up at the expected rate?

Bottom line - maybe the engine temp is just fine... the gauge just isn't accurate due to bad voltage stabilizer, bad sender or... even a bad gauge.

[Jdnewberry]

Where and how are you measuring the temp after running? So a 74 thermostat is equal to 165F, 100C=212F. Like darbsclt says make sure you have the correct stat ^^^^. Not sure but TeriAnn might have it on her website. http://www.expeditionlandrover.info/

It is the correct stat. Temp is measured two ways: first, I found a nifty radiator cap at the parts store that has a thermometer built in and second, I have an infrared thermometer. The rad cap is graduated in both Fahrenheit and Celsius.

[Jdnewberry]

A few things that would be helpful in diagnosis:

-an infrared thermometer would be helpful in determining your coolant temperature at various points in the system
-check your plug color for evidence of correct mixture (light brown ash)
-bubbles in coolant or coolant loss indicating a gasket failure or crack

Plugs are the proper color, but may be accumulating slightly more ash than I would like to see. Not much, though. No visible bubbles in coolant, no oil in coolant, no coolant in oil, and no steam from tail pipe. I don't think it's the head gasket, but I'm not absolutely certain.

[Jdnewberry]

Keep in mind... running the engine at temperature without a thermostat will simply cause the coolant to flow through the bypass port rather than the radiator (the 'stat skirt blocks this port when functioning properly). This can cause the engine to run hot.

As Ignotus referenced, Teriann has a nice write up HERE (http://www.expeditionlandrover.info/Thermostats.htm)

Thanks for the info. I wasn't aware of what the skirt actually did.

[Jdnewberry]

Does your gas gauge work?

I ask because, if it doesn't, it may be that your voltage stabilizer is not working and feeding your temp gauge and gas gauge the wrong voltage... and causing both to be inaccurate. It's harder to tell something's wrong with the temp gauge, but the gas gauge - it's more obvious if it's off. If the gas gauge is not accurate, try swapping out the stabilizer.

Also, consider the temp sender... Mine recently bonked. I noticed it when, within a minute of starting the engine, the gauge showed the engine as mid gauge on the temperature gauge... Does it warm up at the expected rate?

Bottom line - maybe the engine temp is just fine... the gauge just isn't accurate due to bad voltage stabilizer, bad sender or... even a bad gauge.

I have already been down that path. I purchased a new sender because mine didn't work when I purchased the truck. After installing, I noticed it running close to the red. The fuel was also inaccurate, so I drug out the old analog voltage meter. Stabilizer is fine. Looking deeper, I came across the radiator cap with the thermometer built in and verified the temp was high. I also pulled the fuel sender apart and found the wire windings are broken near the 'half tank' mark. That explains why it only holds 5 gallons when it hits empty!

Warm up time seems as expected. It takes 10-15 mins at idle or 2-3 mins of drive time. The gauge stays smack in the middle of 'N' indefinitely until I get up to highway speeds. The mechanic suspects the radiator, but I just can't see that too fast of a flow rate could cause this.

[bugeye88]

Another thing to check is do you have the full fan shroud in place around the fan? If not you may want to install a thermostatic controlled electric auxiliary fan. The "Pusher" type in front of the radiator fits best.

Cheers,
Rob
Bugeye88

[Jdnewberry]

One of the first things I did was add the shroud. Since this issue didn't show up until the weather warmed up, I just assumed the missing shroud was the problem.

My mechanic said that if I was running lean I would feel it in lack of power, but I'm still skeptical. I'm going to order a larger main jet today and see if that does anything. He may be right, but for $5 I can find out for sure.

[SafeAirOne]

Are the fins in your radiator damaged or clogged up with bugs/debris/mud? Is there anything blocking the flow of ram air into the radiator?

[Jdnewberry]

It's pristine. The radiator is only 6-7 months old and has never been off road, so no mud. No bugs either. I have already been that route.

[SafeAirOne]

You're not making this easy, are you? ;)


I don't know about the "too much radiator flow" theory. Hundreds of thousands of these vehicles haven't had a problem with the same setup; What makes yours different? If your radiator is a stock radiator, and your water pump isn't on steroids and the coolant is going where it's supposed to, then I think the only thing left that could have that much effect on the coolant temp is a head gasket issue or damaged head/block as Ike listed before.

What are your engine-hot compression numbers?

[o2batsea]

Anything over about 25-30 MPH the engine fan stops doing anything. Prolly the 4 core is keeping the airflow below optimum. That is, the wall of air that you push isn't getting thru the opening, and the engine fan, having lost effectiveness, isn't helping.
It may be counterintuitive, but try removing the fan shroud and test driving it.

[Jdnewberry]

The compression is a little off, but not extremely bad. Cyl 1 is 150, 2 is 140, 3 is 170, 4 is 160.

I don't think it's the gasket since I'm not seeing the typical signs, but I haven't ruled it out for sure. I also can't imagine that's it's the cooling system with as much as I've replaced and inspected. I don't think it's the head, because that was just worked over by a well respected shop.

A problem in the block is possible I suppose, but unlikely as the engine only has 27000 miles. I question the fuel/air ratio and have ordered some larger jets, but could it also be a weak fuel pump? The inline fuel filter never fills more than 1/3 full, but the engine never cuts out like its starved for fuel. I don't know that a weak pump could cause a lean condition, but I'm grasping at straws.

[Jdnewberry]

Anything over about 25-30 MPH the engine fan stops doing anything. Prolly the 4 core is keeping the airflow below optimum. That is, the wall of air that you push isn't getting thru the opening, and the engine fan, having lost effectiveness, isn't helping.
It may be counterintuitive, but try removing the fan shroud and test driving it.

I'll try that this afternoon. The shroud was one of the first things I tried when it started running warm, but it only made a difference at idle. I have found more things that have lowered the temp, so I suppose the shroud may be in the way. It's definitely worth a try.

[Jdnewberry]

Re-jetting the carburetor and removing the shroud didn't help. I'm going to try the head gasket just in case. Any thoughts on the type of gasket? Copper or composite?

[SafeAirOne]

If it were me and a composite gasket was available, I'd be using that. No re-torquing required and they're designed to bond to the block and head once heat and pressure is applied. Need CLEAN, flat surfaces, though.

[Jdnewberry]

If it were me and a composite gasket was available, I'd be using that. No re-torquing required and they're designed to bond to the block and head once heat and pressure is applied. Need CLEAN, flat surfaces, though.

That's what I was thinking. The cleaning is what I'm dreading, though. It has a composite right now and I hate the thought of scraping the old gasket.

[Jdnewberry]

Sorry it's been a while since I've updated the thread. Been a little busy lately!

I have determined it's not the head gasket, so my thought is that it's running lean. I increased the main jet in the carb, but no change. If it is the fuel, then it's most likely somewhere between the tank and the pump.

I did notice something today, though. I have one of those clear inline filters between the pump and carb and it had bubbles being pumped into it. If a fuel pump is failing, could it draw air? I have checked the fuel line connections and even added hylomar, so I doubt there is a leak in the lines, but anything is possible. What are the odds that this has been my problem all along?

http://youtu.be/okFqxo9kMXk

[SafeAirOne]

http://youtu.be/okFqxo9kMXk#sthash.4MqRcGHg.dpuf

I don't know that that's your problem, but it ain't right.

[Jdnewberry]

Well, I'm going to try a new fuel
Pump and see what happens!

[Jdnewberry]

I fitted a new mechanical fuel pump and also an electric pump next to the fuel tank. Still overheating, but I do have more power at highway speeds. I suppose that's a bonus, but I'm still trying to figure this out. Any more ideas?

[ybt502r]

Well...I hesitate to add to the confusion, but you stated at the start that your radiator is only giving you a delta temperature of 10 degrees from top to bottom. That's not much cooling. I haven't put a thermometer on mine, but I recall that I could feel a difference in temperature between the two hoses, and I don't think my hand could tell the difference between 200F and 190F for example. I'd pull the radiator and have it checked out by a shop. You've pretty much overworked everything else.

[Jdnewberry]

The radiator is a new 4-core, just purchased last fall from RN. I'm starting to think that the myth about radiators flowing too fast isn't a myth after all. I made a make-shift flow restrictor the other day and installed it in the top radiator hose. It's amazing that it actually helped. I'm still running warm, but not as bad as in the past. I'm planning on trying another one with even less flow to see what happens.

[Brian Holmes]

I don't know if the too fast flow idea applies to the LR. If memory serves, the 21 and 59 series (casting numbers on bell housing) flathead Ford V8s used in stock car racing in the 1940s had restrictors placed in the outlets of the heads. My non-stock car but mildly hot rodded 1940 Ford would throw coolant out the overflow when revved up a bit much.
Cheers,
Brian on Kootenay Lake

[SafeAirOne]

Interesting. If too much flow through a 4-row radiator is the problem, then you're seemingly a unique case, as I don't recall ever seeing anyone else write about overheating issues with a 4-row radiator before. Not that it hasn't happened to anyone else, but I'm surprised that nobody's ever mentioned that happening on a 2.25P engine previously. Perhaps something's different about this batch of 4-row radiators?


Are you using an alternative fluid, like Water Wetter or just a 50/50 water/coolant mix?

[Jdnewberry]

Okay, I'm still grasping at straws here. The entire cooling system is new and clean, the entire fuel system is new, but it still runs a little warm. Is it possible that any of this could be electrical? If any condition was causing a weak spark, could that possibly lead to an engine running warm?

I ask because I suspect my coil may be on its way out. The only other ignition component that has not been replaced are the plug wires. I have not checked their resistances, though.

[warrenperkinson]

I'm just throwing this out as a possibility - but are you certain that the temperature before your head rebuild was any different?

If the connection to the temp sender was previously gunked up with oil and the electrical connection was poor, wouldn't the temp on the gauge read lower than the actual temperature?

As part of the rebuild, you probably would have disconnected the temp sender unit and so reconnecting it may simply have given a better connection... and therefore a higher temp reading...

Just a thought...

Warren.

[Jdnewberry]

I honestly have no idea what the temp was before. The old sender was dead. All I know for certain is that the reading from the new sender is accurate. I verified the temp in the radiator with a thermometer.

[slowmo]

Bad timing can cause overheating. When it was timed, was the vacuum advance disconnected?

The first time put a timing light on my truck after I bought it, it was so far off I thought the previous owner was out of his mind...even though the truck ran OK. I got everything aligned as was in the book and it ran "OK" but hot. I monkeyed around with it for a while with no joy, and decided to just time it by ear and see where it ended up. It ended up right where the previous owner had left it. "Dog gone it. What is going on here," thought my tiny little squirrel powered brain?

Suddenly remembered to disconnect the vacuum advance and the wacky thing lined up perfectly. So it wasn't the previous owner who was out of his mind after all. Hmmm.

Anywho, you might check it again.

[Jdnewberry]

I wish it was timing, but I doubt it. I'm willing to try again, but I have set it statically and dynamically. (Vacuum disconnected for dynamic) it is an emission controlled engine, but I do no have the carbon canister.

That said, it runs best at 6 deg btdc, but it still runs warm from 6 atdc through 18 btdc. Also, when I say warm, it isn't in the red. It touches the red, though. It also becomes very difficult to restart at that temp. After a few cranks, the cool water in the radiator cools the engine enough to fire.

I know it seems hopeless, but there must be an answer. Surely I'm not the only one with this issue.

[clearcut]

I had timing set in Sacramento at repair shop
ran great. then a few weeks later found the vacume was disconnected. now it like a race rover

[cedryck]

When you disconect the tube for the advance, do you disconnect it from the carb of dizzy? Do you plug it after disconnecting? Inquiring minds want to know,,,,

[clearcut]

I think the proper way is

Initial: This is the most common adjustment that people associate with timing. At idle, with the vacuum advance hose disconnected and plugged, this is the timing that you would see if you flashed timing light on the timing marks. On typical stock engines you'd see as low as 0 to as high as 15 degrees. Most Ford shop manuals specify around 6-8 degrees initial timing advance for the 289-351 motors.


My question would be what due you plug? Going to Motor? Going to vacuum?

My vacuum pipe was broken by the carb side of motor, then fixed with a rubber hose that was not connected!


josh

[slowmo]

The important thing is to set the timing with no vacuum advance at the distributor. I disconnect at the carb because it is easier to reach. I plug the vacuum fitting on the carb so it isn't pulling in air which matches normal running condition. Then set the timing. It is amazing how far off the timing mark is with the vacuum advance connected.

[joulandy]

Hi,

Did you resolve the overheating issue? If so what did you find to be the cause.

Also what should the delta T be for a good functioning cooling system.

Andre