TR7 oil pressure/crankcase pressure

[Hasbeen]

Ah yes Mildred, with those low cut doors, the air conditioning worked very well, particularly of the kidneys on a cold day.

That road had one really big advantage.

No speed limit, & no cameras with evil intent.

Hasbeen

[FI Spyder]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Hasbeen</i>


We found the problem with the UK car industry with that car. We picked it up from the company with 4 miles on it. It had 17 when we stripped it to detail it, but some of the big end slippers were so scoured they had lost about a third of their area.

We got half a spoon full of swarf out of the camshaft alone, no wonder they did not last.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Back in the day I worked with a guy that came over from UK that fixed IBM equipment for a third party and drove across England in the course of his duties, putting on lots of miles on his Imp. He said it had to be overhauled every 30,000 miles.

Don't blame the Brits....blame the Scots, that's were they were made.[:p][:D]



- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[moodyblue]

If the suction at the intake manifold sucks through the canisters to the valve cover to suck the vapours into the engine, it's strange that there is any blow around the filler cap, but it does happen.
My engine has only 2300 miles on it and even with 2 cork seals on the cap oil gets out. It likes to force it's way out of the tightly sealed cap rather than through the easiest route via the breather pipes, which are all clear.
First oil change since rebuild today and still the same[:(]

[Workshop Help]

Well, actually, the down stroke of each of the pistons is what creates the suction. This suction, which is tapped via holes with fittings on the intake manifold, is drawing oil vapors, gasoline vapors, and air itself from brake boosters and distributor diaphragms. All these vapors are being drawn into the cylinders by the piston down stroke suction.

All this piston suction creates a positive vacuum pressure inside the engine crankcase. If an engine has a blockage to prevent the venting of the crankcase oil vapors, this built up crankcase pressure will seek an escape past a weak point such as the filler cap, oil dipstick, or a vent hole in the fuel pump.

Since on a TR7 engine the prime venting hole is the tube on top of the valve cover, I suggest you investigate there first. Try a blast of compressed air and see if it roars into the head. If not, take the Valve cover off and degrease the vent area. Proceed down stream to the carburetors and hose fittings.

Mildred Hargis

[Hasbeen]

I think the reason some oil escapes from our filler is the position, right over the timing chain. Centrifugal force throws a lot of oil off the timing chain, as it goes round the cam sprocket when the revs are up.

Mine has suction at the filler pipe, when the cap is off, but when we had the cap off once, my son gave the thing a good rev. Very small droplets of oil sprayed out the filler, all over the engine bay, front fenders, & even some onto the windscreen.

The amount of oil that must hit the underside of the cap at high engine revs, would quite high.

Hasbeen

[moodyblue]

Thanks for the detailed description Mildred. The pipes are clear and I gave them a blast of lung power to check. Even my old welder/smoker lungs managed to blow through from the carb pipes to the rocker cover without a problem. Hasbeen, you make a good point about the location of the cap and I would be surprised if there was no spit of oil with the cap removed. Having said that mine is really bad and more than a spit with a well sealed cap on. It has started running very, very rough when cold and I have to drive for miles before it improves, and even then it's still not great. The last time I had a wedge run like this it was water in the fuel due to blocked drainways around the filler cap. It's been hammering down with rain here for the last few weeks but I can't see how that could happen on this car, but I will check the float chambers. I will also check the plugs and compression while I'm at it, but it's my only vehicle other than my other stripped TR7 so it better not be serious or I'm in the ....!