Bugeye overheating - help please

[ichthos]

Finally got the Bugeye on the freeway the first time for a test drive. Drove through town for about 10 minutes and then onto the freeway. After a couple miles at 60mph, the temperature started to climb and made it up to 190. At the same time the oil pressure dropped from 50 to 25. I pulled over to the side and shut the engine off. I sat there for 45 minutes while it cooled down, started it up and made it to the next exit. The same thing happened and I decided to just get a tow home for the remaining 6 miles home. Any idea where to start to figure out where the problem is?
Kevin

 

[Deleted member 8987]

Well, it's not the fan. Don't need a fan on the open road. Thermostat, probably not. If the temp holds okay in town, it's opening as it should be. Not saying it's failing at the high end, but not likely.
Collapsed lower hose at high RPM's, seen that in other cars a lot. Retarded timing, but I thought you'd checked that all out.
Bad water flow in the block/head.....rust, scale, dead rats.
Steam out the tailpipe?
Oil pressure dropping happens when they get real hot.
Pluged radiator. You had it recored, replaced, or rodded out?

 

[BugeyeNJ58]

List of things to check:
-radiator hoses;are they in good shape
-is your fan working correctly, is it pulling the air in towards the engine
-what shape is your radiator in, has it been flushed, is it new
-is your thermostat working
-is your radiator filled with water/antifreeze
-is your timing correct, if it's too advance it will cause overheating.

I'm dealing with some of these issues on my 1275 BE, been there done that. Do you have your heater hooked up. I didn't, but recently attached a hose from the heater valves back to the radiator and it definitely helped.

Keep the list updated. And more details, is it an original downflow, or updated to crossflow?

 

[ichthos]

So, it looks like this is a coolant system problem? Is there any reason that the oil pressure would drop other than the engine just getting so hot - can oil problems cause coolant problems?

I forgot to mention that my wife was the one driving through town. I took over on the freeway and didn't look at it until the temperature had already started to climb, so I am really not sure how it did in town. To answer your questions, I boiled everything out when I rebuilt the engine, including the head. The fan blades are installed correctly. All the hoses are new. The water pump is new. The valve is open to the heater, which is hooked up. The stock vertical flow radiator was checked and rodded. I even had the heater "radiator" checked. The radiator is filled with antifreeze. The thermostat was new - do I still need to remove it and test it? I figure I could put it in a pot of water and as it heats up, I could check it with a thermometer when it opens up. I am fairly sure the engine is timed correctly - it starts right up and runs smoothly.

One thing that bothered me is that the crank pulley looks a little warped - would that cause any problems? I have a spare crank pulley, but I wasn't sure what would happen if I loosened up the crank bolt to replace it.
Kevin

 

[leecreek]

radiator cap? I had one where the little ear on one side that grabs the radiator neck would slip off.

 

[JPSmit]

Two thoughts.

1. a normal thermostat is 180 deg. If your car is showing 190, it might be that nothing is wrong but your gauge needs calibrating (which isn't worth doing for that little deviation BTW). You can get a summer (cooler) thermostat



2. Oil pressure will drop with temp - what weight oil are you using?

 

[regularman]

Get s pressure tester for a cooling system an pressurize it and look for a leak.

 

[nomad]

Hey, here in the midwest it ain't hot till it hits 212!! That doesn't sound all that abnormal if you were trying to run freeway speed. The oil pressure on the other hand???!! Hope you were just running too light oil.

Kurt.

 

[Trevor Jessie]

Mine runs 190 on a hot interstate run and 195 in stop and go hot traffic.

 

[Trevor Jessie]

So, my question: was it going to level off at 190 or go higher? You should be able to safely run it in the 200-215 range for a short duration.

 

[ichthos]

The radiator cap is fine. I am running Valvoline 20/50 racing oil. When I said the temperature gauge was 190, I meant that was what it was when I shut it down - it was still climbing. With the continued reduction in oil pressure (50 to 25), I did not feel it was safe to continue. I don't know if it is worth mentioning, but the first time it got hot, I was also starting to lose power.

One of my first suspects was the head. I did have problems with the first head gasket, and had to replace it with a Payen gasket. I don't know if it makes difference, but the engine had been sitting for years after I rebuilt it. There is no anti freeze in the oil, so I don't think the head gasket is leaking. There are no other leaks I can find so far either. Since this is the first car I have ever done a total restoration on, anything and everything is suspect. I am going to pull the thermostat later and check it just to be sure. Anything else I should be checking?

Kevin

 

[nomad]

I think check the dipstick for metal. If its been sitting for a while it may hve settled out though. Did your thermostat have a bypass hole? Some don't in which case it is possible to not get coolant up to the thermostat on start up therefore it doesn't open.

kurt.

 

[smaceng]

At this stage, I would do a compression check. that way any head or head gasket problems should show up. My car in hot weather and in stop and go will climb easily to 190 to 200, even with recorded radiator. I'd worry about the oil pressure and the losing power. Was the 25 psi oil pressure at speed, or at idle? The temperature will go up after you shut it off, as there is no circulation, and less cooling.
Scott in CA

 

[ichthos]

I am not sure how much I will get done today since I will have to leave shortly for a fourth celebration with the family. Thanks for all the suggestions.

To respond to your comments/questions, I have one of those magnetic drain plugs, so something should show up if there is any metal. I wanted to remove the plug so I can see if there is any radiator fluid anyway. I do have a bypass hose. I am not sure how relevant the high temperature was (190) for diagnosis since it was still climbing when pulled over and shut everything off. The 25 psi is what it had dropped to from 50 (and probably would have dropped further) while I was driving on the freeway. I checked the owners manual and it stated that running temp should be 165, and the oil pressure should be 60, with idle psi at 15 does this sound correct?

If I do a compression check, how will I know if the problem is with the piston cylinder or the head itself? I will go out and do this and repost if I get time.

Kevin

 

[jlaird]

That is not right, 60 lbs on cold start, maybe 40 when 180 degrees and running down the road, 10 lbs at idle. 20 lbs is fine for limping home carefully at some speed.

Temp 180 is perfect. anything under 200 is fine.

 

[aeronca65t]

What temp thermostat are you running? I'm running a 165F thermostat in my street car (MGB) and that works out fine.
I ran the same thing in my old street Sprite too.

Also, are you running *pure* anti-freeze? If so, this will cause overheating, since pure anti-freeze does not reject heat well. The best ratio for these cars is somewhere around 1/3 to 1/2 anti-freeze (and the rest should be pure water).

It's a good idea to make sure you don't have excess air in your radiator. With engine cold and cap off, squeeze lower hose to "burp" out any air.
And since we're talking about the lower hose, it's already been mentioned above to watch for a collapsing hose, but worth double checking, even with a new hose. Start the engine and warm it up. Have someone rev the engine while observing the lower hose. Make sure it isn't sucking closed. Some of the Asian-sourced hoses aren't that good.

 

[TulsaFred]

1. Get a IR temp gun at Harbor Freight for $29 and check to see whether it is really getting hot. Gauge calibration often inaccurate.

2. If compression tests ok and water circulates, then the Radiator is suspect.

Fred

 

[Deleted member 8987]

I would suspect if the oil pressure dropped off that significantly, it is getting that hot. I would guess his gauge is reading low.

I would ask what was the coolant level when the engine cooled off at rest?
If it's so far down below the tops of the tubes you cannot see it, you need to check for leaks.

Once you have a 50-50 mix, and then start it up and run it with the cap off, do you get bubbles or foam in the top of the radiator?

 

[ichthos]

The radiator fluid was at the correct level - well above the tops of the tubes. I am currently draining the radiator (the fluid sure runs slow out of the valve.) And yes, I <span style="font-style: italic">was</span> running 100% radiator fluid. I will do a 50:50 mix of water/radiator fluid as suggested, start it up, do the rest of the checks suggested and see what happens. My wife is picking up an infra red thermometer from HF on the way home tonight. I checked my records, and I do have a 180 degree thermostat in. I will definitely be putting in a 160 as soon as I get the chance.

I did a compression check and got 170 for all four cylinders. The two front plugs were colored brown, but the back two were black. I am guessing I have it too lean to the back two plugs? My biggest worry is having to take the engine back out. I am having surgery in two days, and I will not be able to do much for a couple of weeks.

Kevin

 

[smaceng]

Kevin, all good ideas and am glad the compression test was good. If the plugs are black, that means they are too RICH.Clean the rear plugs, turn the carb adjusting nut 1/2 flat cclockwise from the bottom, then check again after time.
Scott in CA.