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Running too hot up grades at speed

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Kim de B

Kim de B

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I was planning to drive the 66 B up to Vermont this weekend for the British Marque Club News Triathlon event. It's about a four and a half hour trip from here. We can't leave until noon Friday, so need to take highway (the New York Thruway) for most of the trip -- first three hours.

I'm still eating oil, about a quart every 200 miles. But that's not what I'm concerned about, since I can always pour in oil.

My dilemma: The car is running hot, hotter than it used to, when running at highway speed and up grades. With the oil topped off, I just took it on a 20-mile run on the interstate, over a section that climbs steadily up. Air temp is about 75 ° F, maybe about 80 ° in the sun. Not that hot.

By the time I got to the top of the grade, running at 65 mph, temp gauge was pushing 230°. (The top end of the gauge.) When I turned around and came back down the grade on the highway, the gauge started dropping down to its normal 190°. (Where it ought to be.)

In normal traffic around town, and going up regular inclines, it climbs to 212° too easily, at least compared to what I've been used to. But it does come back down when I get going down around the back roads, not climbing hills.

The radiator was recored last year, and flushed out two months ago after we got back from St. Louis. Just don't know what is making it run hotter than it used to.

My immediate question: If you were me, would you drive it to Vermont on Friday? Vermont is definitely "up" from here.

I'm not going to have an opportunity before Friday to do anything major to it.

What are my risks if I take it and drive it at 220°+ sustained temps?
 
I take it you're burning oil, or is it leaking elsewhere --- and what's the oil pressure? I'm just wondering if there's a problem related to your loss of oil that's causing engine temps to rise.
 
I asolutely agree with Scott.
Friction causes heat, and increased oil consumption, coupled with a rise in coolant temp is not a good thing. To me, it's a sign of impending failure, and I wouldn't chance the trip "up" to Vermont. Of course the temp goes down on a downhill segment, because the engine is essentially under a "no load" condition.
I hate to be the bearer of bad news, but peronally, I would stay home, and find the root cause of the problem, before I did some major damage.
What is the oil pressure doing? What about throttle response as the engine heats up? Does the oil pressure follow the temp gauge, or vise-versa? Troubleshooting online is tough, if you don't have all the data.
Look at it this way. If you were flying to Vermont, and as you were taxiing out to the runway for takeoff, you overheard the pilot mention something along the lines of, "Would you look at that! This thing has never done that before!", would you be comfortable?
Jeff

[ 08-20-2003: Message edited by: Bugeye58 ]</p>
 
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What are my risks if I take it and drive it at 220°+ sustained temps?
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Probably serious damage to the engine & a trip home on a truck.

It would seem that it already has a serious problem. You don't say if it is burning the oil or leaking a lot. A compression check would help to determine the problem. combustion leaks past the rings will definitely cause overheating.
D
 
It's not leaking oil, so must be burning it, although I'm hardly getting anything noticeable in the way of smoke.

I agree that they must be somehow related, and reluctantly will be leaving the B at home.

I haven't had a chance to run a compression test yet, but did pull the plugs, and they're clean as can be. Same goes for the PCV valve.

Oil pressure is good, hanging in at 60 at speed. Didn't notice that slacking off when the temp gauge went up, but that's something I look at next time around.

It seems to be running OK, although I notice a lack of power pulling out from a stop in 1st gear.
 
I wouldn't chance a long drive either....but your oil pressure is good, and that's a good sign.

1. Check to see if lower hose is "sucking closed" at higher RPMs (look at it while someone revs the engine).
2. Be sure that ignition timing is OK. Retarded timing can cause overheating under load. Put a timing light on it and see if it's advancing when you rev the engine.
3. Is collant mix about 50/50?. If you have too much antifreeze, the car will overheat (antifreeze doesn't reject heat as well as water).
4. A cooler thermostat may be a good idea (if you don't already have one). I'm running a 160 in the Spridget. Remove the thermostat (as a temporary solution) and see if it runs much cooler without one.
5. Even if your fan belt is tight, it could be slipping under load if it's old and "polished".

As for oil consumption....

1.Your don't have a stuck choke....do you? A rich mix will cause oil consumption. Also a "high" float level. Dirty air filter can do this too,
2. Even if the PCV valve is clean, it could be stuck "open", applying vacuum all the time. Temporary fix. Vent the crankcase to the atmosphere (remove the hose going to the crankcase vent....I can't recall if this vent is in the valve cover or side cover in your car). Be sure to plug the hose you've remove from the vent. See if oil consumption is reduced.

G'luck.
 
Kim...here are a couple of thoughts:
1) Oil pump..is it pumping at correct levels? You may be getting inadequate oiling to internal engine parts causing the engine to 'heat'.
2) water pump...is it also 'lazy'? Coupled with bad oil pump, a water pump on its last legs can't handle the extra heat.
3) oil usage...are you seeing any type smoke when you initially start engine or during heavy loading? what's the end of your tailpipe look like - clean or oily?
Now, & I've gotta ask the question: what's the outside of your block look like? Is it clean? If not, steam clean it & start watching...how's the undercarriage around the rear main seal/transmission look? Is it oily? Steam clean & start watching...
...&, kiddo, I'm afraid you're gonna be using that tent for something other than storage this winter! (Just don't disassemble your engine & put it on your bedroom floor on your mother's clean, white sheets - tends to cause problems when she comes in to deliver your clean underwear!)
 
Some women just don't have a sense of humor.
nonod.gif


[ 08-21-2003: Message edited by: mrbassman ]</p>
 
I think we have a diagnosis of the probem on the MGB Experience board.

Before going to St. Louis, a friend of mine helped me tidy up the engine. One of the things he did was hook up the vacuum advance, which had never been done. (Tube was attached at 25D distributor, but just hanging loose.)

He hooked the advance to the rear port on top of the manifold. Gary saw it in St. Louis, and said it should be hooked to the rear carb. Someone else looked at it and thought it was OK where it is.

But now I'm getting a consensus that it needs to be connected to the rear carb, and that my timing was now too far retarded.

What say you -- Could this be causing both the oil consumption and running hot problems?
 
Kim, first of all if your plugs are clean then you don't have an oil consumption problem. I can assure you if you were burning oil you would see the results with black and wet plugs. You have oil leaking somewhere. Tony's suggestion is mine. Either take the car to a car wash, put it up on jack stands, and gunk the engine, tranny, and bottom of your car down real good. Then blast it off. I would take the air filters off and put duck tape over the cards so I could get to the tappet cover area real good. Also take a roll of paper towels to dry the distributor cap real good. After that drive it for 30 min or so. Next dust the engine with baby powder. You will find the leak. Or you could take it to a shop and spend $75-$100 and let them do it. To answer you question I don't think the advance hook up is your problem. To find out pulg it and drive it.
 
OK, Tom, I'll check for a leak. (There's absolutely nothing dripping under the car when I park it. But maybe something else weird happening, where I only leak oil under pressure when I'm running?)

And ... what about my running hot problem? Is this one problem or two?

And ... so you're saying it doesn't matter where the advance is hooked up?
 
Kim, it could be leaking and blowing back under the car. I'm saying it wouldn't effect the temp as much as you are having. Did anyone even check to see if the vacuumn advance is even working.
 
chuck....You don't wanna know what my mom said...t was a straight-8 engine I wanted to put in a 1948 Pontiac...it was clean before I spread it out on the sheet! 1st engine I ever took apart & rebuilt...she's never let me forget it either - &, I'm 57!
 
Kim, Join the 200 mile per quart club.
smile.gif
I don't have the heat problems you have, but everything about your oil consumption sounds like mine. I haven't checked my plugs recently - will do that this weekend... along with a few other ideas. My 71' B just started losing that much oil this year, but over the last 20 years I didn't burn more than a quart all summer! If you find out what's happening with your oil consumption, I'd be very interested in your findings!

My engine runs fine as far as I can tell, except for a rough idle (the carb bushings -vacuum leak). So the engine seems fine, doesn't smoke, and seems pretty smooth (but I can't compare it to other B's though).

Isn't it strange to have a car run through that much oil without smoking? I don't get it, unless there was a major leak. Maybe you're right, a small leak increases with pressure due to higher RPM's while driving. I do have a very small leak in what appears to be the rear seal (extremely common), and it's been there for as long as I've owned the car. Maybe it's getting worse as it ages, and starts to spirt out at high speeds?

BTW: Have you made any modifications to your engine or emmisions?
 
Kim....if the oil is leaving the engine while you're driving, there wouldn't be a puddle underneath - its all blowing up under the car, undercoating it so it'll never rust! (Hey, gotta find a positive in everything related to these LBC's!)
 
Yeah, I hope to get the car up on my friend's lift on Monday and take a look. Maybe there will be clues. We'll check out the vacuum advance and make sure it's working, and run compression, and just see what's what.
 
Low compression has nothing to do with worn oil rings. If anything worn oil rings improve compression. I never understand why people say to do a compression test in connection with a car loosing oil. A compression test is for the valve seats, and top rings of the piston. It for compression not oil consumption.
 
Tom,
I originally suggested a compression check in conjunction with the overheating problem. Hot combustion gasses blowing past the rings & down the cylinder will noticeably increase the heat load on the cooling system. Part of the combustion heat is lost to the cooling system instead of producing power.
D
 
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