Cooking at Gas Mark V8 - hot engine.

R

Rovertron

Member
Hi all,

I've got a slightly cooking V8 and it's left me scratching my head.

Just want to run this past you... Been taking the P6 out and as usual at some point, you have to give it some welly :D

The car and I enjoy this (the wife likes to white her knuckles on the seats) but lately, speed and load including a nice 60mph 1:5 hill near home pushes the engine temp up just slightly and then it returns to 85. It got a 40 mile run today and plenty of national A-roads, a few steep inclines and it was a hot day but on the way home; it started to cook. I have a Kenlowe on the car (thank god) and it was holding it ok at 90 but it was refused to cool back to 85 over the last 5 miles home. I had to vent hot air into the car, the wife wasn't impressed seeing as it was about 80F today.

I've checked the coolant which is fine and regularly changed; all the usual overheating trouble sources are either new or recently set-up (Dizzy cap, condensor, rotor arm, coil, HT leads, sparks), it gets V-Power + Valvemaster and the timing was only reset at the last service.

I let it cool down a while then took it out for a run all seemed fine. I let it heat up at idle and took it out, again, it wouldn't cool back. I did the old broom handle trick to the water pump to listen in and there was some kind of graunching sounds, like metal with little lubrication grinding together.

The car has always got hot sat in traffic (hence the Kenlowe) but it does return back quite sharpish to the mid-point between the 8 and 5 on the gauge after some air gets into the engine bay (usually 1/4 mile @ 30mph is enough). The water pump looks newish as the aluminium is fairly bright and the clips holding the hoses on don't look too old. What's the considered opinion of the forum?

Is it something else or is the water pump lunched? I've heard of the pump stators wearing out and reducing the flow of water round the engine.

Many thanks in advance.... I'm stumped.
 
Check that the vent pipe that goes from the top of the rad to the top of the inlet manifold has not got blocked, either the hose itself, or the metal pipe that goes into the manifold.
You could also check the rad for cold spots, and see if there is any play in the water pump by rocking the fan blades.
 
Sorry to hear about the pressure cooker.
The first thing to check would be, as previously mentioned the small pipe that runs from the rad to the inlet manifold (ensuring the metal stubs at each end are not corroded up).
Then check the rad cap for correct sealing (rubber perishes & spring breaks). Thermostats sometimes don't open fully, causing flow to reduce at high RPM. Check the rad for obstructions, check carbs not too lean (weak), oil & water levels ok?
Timing OK? Too advanced will cause high temps.
Lastly, i once had a car that did what you mention, it turned out to be a blocked rear exhaust box. Does the car seem to "Hold back", as if dragging a tree behind it?? If so, go for the exhaust.
I hope this helps a bit.

harveyp6 said:
Check that the vent pipe that goes from the top of the rad to the top of the inlet manifold has not got blocked, either the hose itself, or the metal pipe that goes into the manifold.
You could also check the rad for cold spots, and see if there is any play in the water pump by rocking the fan blades.
Click to expand...
 
Thanks guys, plenty to go on here for the forthcoming weekend. I was going to get to it on the Sunday but what a throroughly depressing affair that was.

I'll check the play first in the water pump as it did sound like some shot bearings in the case. I'm tempted to go through the cooling system a hose at a time to see what's what but will defo start on the inlet manifold setup.

Of course, will post up if I hit another dead end ;) or solve it. :)
 
Hi Guys,

The weather held off enough to get out for a while this afternoon. There was a little play on the water pump fan but it wasn't so great to have me concerned. I remember taking the fan blade off for the Kenlowe install about three years ago and the play was about the same. There's certainly a metallic sound coming from it so I think I'll look at getting a replacement at some point, it looks an easy enough job in the workshop manual.

So I completely bled and flushed the system, both from the manifold heater input, a reverse flush of the rad (disconnected from the engine) and then a full drain through the rad drain plug.

So looking at the manifold hoses, they looked fine. I pressured the system using the pressure release hose and the outlet was blocked, it looked a little corroded too which gave me some idea that I've been running short of sufficient coolant for some time. I managed to get a very small screwdriver in there to unblock it. (Harvey, you're a star :) )

Then using a garden hose attached to the release hose, it certainly was relieving pressure :)

So I recharged the system with 50% anti-freeze. I also think the heater had vacuum locked a little (which it's definitely has done before). I usually have to take the heater outlet hose off and fill from there (with the outlet corked) to get rid of it.

The good news was it took longer to go over 85F and the engine cooled very quickly once moving which it certainly wasn't doing before.

Thanks again for all the advice, you guys are great. The only downer is using the broomstick stethoscope around the engine, one of the camshafts is a bit noisy when cold. Oh well, the chap at the garage must have hearing like a bat :)
 
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