one exhaust manifold much hotter

corazon

corazon

Well-Known Member
Morning,
Would anyone have a nice quick answer :? to why my driverside manifold heats up to untouchable after a couple of minutes running whereas the other side stays relatively cool/warm??
Unbalanced carbs?
The hotter manifold was newly fitted less than a year ago, as i bought the car with a cracked one.
Is there something underlying here?
 
Hello corazon,

Each carburettor feeds the two cylinders at each end of the head on its own side along with the two middle cylinders on the opposite side, so a lean fuel mixture (which burns much hotter) would seem not to be the likely cause.

I would be inclinded to point a finger at a coolant blockage within the offending cylinder head. If the coolant cannot flow through, the the heat generated by the exhaust valves will rise rapidly. That may also explain why the previous manifold had cracked.

Ron.
 
Ron thanks,
I've had cooling problems on and off since i've owned the car.
She gets very hot in traffic, but the kenlowe keeps it from the red, jUst.
This is made much worse after driving from speed to a crawl.

Can you explain to me what direction the coolant physically flows in the block?
So you suggest flushing then?
 
Hi corazon,

Not a problem,..hope I can help. The coolant flows up from the rear of the engine entering the cylinder head and the flowing through before exiting at the front into the inlet manifold. To flush you could try a radiator type caustic cleaner to start with allowing it to run through the system for an hour or so (what ever is recommended) and then when cool open the radiator drain plug, the engine taps and allow the system to empty. You could remove the thermostat housing along with the thermostat and then use the hose with vigour to flush as much gunge out as you can, allowing it to all pour out through the taps.

Once the fluid exiting looks clear allow to drain and then close all and refill the system. I hope it all goes well!

Ron.
 
To be honest I'm more suspicious of the cool manifold than the hot one!

It does sound to me like you have a cooling system problem, possibaly as well as other problems. So I agree on starting with a good flush! Don't forget to back flush the radiator and the heater and all its pipework while you're at it! The V8 is generally reckoned to be undercooled, so at conclusion of this you may well still have a problem. If so the next logical action is to get your radiator rebuilt by a local rad shop with a three row core instead of a two row. A surprisingly cheap operation and should eliminate the cooling side of the equation from discussion!

As to why one bank should run much cooler. My suspicion is that you may have some worn cam lobes. Take off the rocker covers and turn the engine over (perhaps motor on the starter motor with the plugs out) so that you can check how much the valves move. It will be immediately obvious if some valves move a lot and others hardly at all. You might then be able to conclude that one bank isn't working very hard because it can't get gas in or out! This is a common V8 happening with very little to show for it until extremis. Solution is a cam and followers change. While you're at it just double check the layout of the plug leads gives the correct firing order!!

I have heard of people on here who have had inlet manifolds badly blocked with gunge and only able to be cleared by removing and physically poking it out. But I haven't heard of heads in that condition.

Since you're going to be having a lot of hoses off, either do a complete hose change or be very sure of the internal state of them before you put them back on. It has been known for hoses to collapse internally and look ok on the outside.

Hope that all helps

Chris
 
A quick update,
I flushed the system as well as i could yesterday, the drain taps were stuck solid so had to all come out rad drain hole and thermostat housing unfortunately.
I'll try again soon depending on results.
I thoroughly cleaned out the inlet manifold return pipe(the metal part), it was completely blocked.
When does water flow back through this pipe?
I also replaced the thermostat with a new one i had, which is an 82 degree one. The one that came out was 74.

Went for a drive and it all seems much better in traffic so far.
It also needed the choke for much less time.
 
Hello corazon,

Sounds so far an excellent result! Hopefully things will stay that way for a time. To keep your cooling system healthy, always flush and replenish to the recommended strength as per the time or distance (which ever comes first) recommended by the coolant manufacturer.

The metal pipe on the inlet manifold tower is a bleed pipe that allows air to escape that would otherwise remain trapped within the manifold...not a good outcome. Coolant flows from this manifold pipe back to the radiator.

Ron.
 
Was it the big pipe which connects to the water pump that was blocked?

A 74* stat is too low in a good system ( I know as I tried it ) sounds like a bodge and a good sign that the provious owner was having overheating issue. So dont be surprise if the gauge goes into the RED.

Colin
 
no it was the smaller pipe on the manifold Colin.
The pipe actually gets hot aswell as the main pipe now, which has never happened since i've owned the car.
Guess it has been blocked solid for a while, causing all sorts of trouble :shock:
So far so good still. Temp still gets up to top of the green in heavy traffic, but has yet to actually go in to the red.
She recovers much quicker too.
 
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