classic car forum header
Classic cars forum & vehicle restoration.
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 
How To Register     Posting Photographs     Privacy Policy     F/book facebook.com/oldclassiccar

Escort Mk2 1600 OHV - crankcase emission control
Post new topic   Reply to topic    Classic cars forum & vehicle restoration. Forum Index -> Ford
Author Message
jessejazza



Joined: 18 Mar 2009
Posts: 75

PostPosted: Sat Jan 13, 2018 4:51 pm    Post subject: Escort Mk2 1600 OHV - crankcase emission control Reply with quote

On a longer journey I have had the suspicion that I am getting a build up of crank case pressure. But what can be the cause? I have had oil coming out of the top of the dipstick, leaking out of the bottom (this dipstick sits in a rubber case which is put on a nozzle in the block).

Initially I thought the oil control valve in the oil separator canister was sticking, found that the rubber had gone and replaced it with another which I was delighted to find I had spare. I also put a jubilee clip round the bottom of the dipstick case so it would keep tight against the nozzle shoulder.

Hoping I'd solved the problem I also looked further. I hadn't had her running as sweetly as I'd like as I found the tickover needed to be increased for idle. She has an ICH 34 carb which was a bolt on replacement for the standard Ford one. I noticed the pipe from the oil control valve feeds directly into the induction manifold below the carb. I'm questioning Ford's wisdom here as my 1300 Escort fed into the air box which seems logical to the intentions of environmental control and vehicles eating their own engine fumes. So why feed into the induction manifold when vacuum is likely to be 20 ins and thus a fair suction on the crankcase. The oil control valve (just a spring with ball on a seat probably lifts at something like <5 psi so little point in the control valve when subjected to 20 ins from the induction manifold. But then I've not understood why the oil filler cap is open with just wire gauze.

So hoping to solve this I put one of the oil filler caps with a nozzle on which I think Ford did later have as standard fitting (my Escort back in the 80's did not I recall). Blanked off the induction manifold with a 1/4 NPT blank. Used a T piece to connect the nozzle on the oil cap with the oil control valve pipe and take that to an oil catch tank and then extend the nozzle hose down to the car's underside which conveniently could be slid inside the engine mount bracket to stop it flapping around whilst on the road. perhaps using an oil catch tank is over kill but without an MOT tester could argue oil would get onto the road.

Took her for a spin and thought she sounded better and returned home to give her a tune. She certainly sounded better and idling at 800 rpm. Over 200 miles later I've found I have still got weeping oil coming out of the dipstick hole and a weep on the base of the dipstick case. The dipstick does not seem to have a seal on it but as oil vapour would go through the oil emission valve. Presumably my next step should be to put on a fuel pipe clip as this could make a tighter seal on the crankcase nozzle, remove the dipstick and replace with a bolt to seal it.

Perhaps I shouldn't have removed the feed to the induction manifold - but I have read of folk having the same problem with SUs on cars and not able to tune the engine to its best without removing the feed to the induction manifold.

Maybe completely the wrong approach - the engine is somehow building up crankcase pressure but what causes it. Incorrect oil used?- she's got 15W40 quality oil which is correct. I'd welcome any advice.
Back to top
View user's profile Send private message
alastairq



Joined: 14 Oct 2016
Posts: 1263
Location: East Yorkshire

PostPosted: Sat Jan 13, 2018 5:14 pm    Post subject: Reply with quote

A quickie response...aside from the pumping action of the underside of the pistons.... worn cylinder bores, worn/broken piston rings, etc can cause crankcase pressurisation.

The take-off from the inlet manifold is to create a negative air pressure in the crankcase.....there ought to be a one-way valve in the pipe somewhere, which might need cleaning out? The negative pressure ensures minimum or zero oil leakage past the crankcase seals....stuff prefers to travel from high pressure areas to low pressure areas....
I would first try cleaning out the hose for the crankcase ventilation system...sometimes they can collapse because of the contact with oily stuff [oil & rubber don't mix]....so a new hose might help?
Back to top
View user's profile Send private message
jessejazza



Joined: 18 Mar 2009
Posts: 75

PostPosted: Sat Jan 13, 2018 7:18 pm    Post subject: Reply with quote

alastairq wrote:


a] A quickie response...aside from the pumping action of the underside of the pistons.... worn cylinder bores, worn/broken piston rings, etc can cause crankcase pressurisation.

b] The take-off from the inlet manifold is to create a negative air pressure in the crankcase.....there ought to be a one-way valve in the pipe somewhere, which might need cleaning out? The negative pressure ensures minimum or zero oil leakage past the crankcase seals....stuff prefers to travel from high pressure areas to low pressure areas....
I would first try cleaning out the hose for the crankcase ventilation system...sometimes they can collapse because of the contact with oily stuff [oil & rubber don't mix]....so a new hose might help?


Thanks for the response
a] The engine isn't perfect but compression test was about 150 psi on all bores - I did think of cracked rings but ruled that out. I am wondering about another cause perhaps - blocked oil gallery or oil pump not performing 100%

b] The control valve would be the one way valve? I found in my boxes after posting a spare. Held it to the lips and sucked - no resistance. Blow and there is resistance i.e. it is seating properly. The hose fitted is the correct type I am sure as it is smooth/shiny rubber different to fuel/heater hose. If the vacuum is removed so there is nil pressure there I can't see how the crankcase seal could leak.

I'll do some more investigation tomorrow.
Back to top
View user's profile Send private message
alastairq



Joined: 14 Oct 2016
Posts: 1263
Location: East Yorkshire

PostPosted: Sat Jan 13, 2018 10:32 pm    Post subject: Reply with quote

The crankcase will pressurise, unless vented. All those spinning things will create the pressure.
If not released, the oil seals will leak.

The Crankcase ventilation system creates negative pressures in the crankcase....so any leaky seals will suck inwards, rather than blow outwards.

Is the rocker box clean & clear?
Back to top
View user's profile Send private message
jessejazza



Joined: 18 Mar 2009
Posts: 75

PostPosted: Sun Jan 14, 2018 9:28 pm    Post subject: Reply with quote

Been looking over her today again. The emission control pipes are all clear. It seems the only reason for oil getting up the dipstick is 'mist' just going up. The dipstick is hopeless - there is no seal or cap on the end. Looking through my boxes of bits I find I have 4 and they are all the same. In theory I suppose the top has a wider section but it is still a loose fit and there is no cap at the top of the dipstick to make a seal.

For the moment I have found a bolt 2" long that makes a tight fit and I'll see how that goes. Just wondering if there was a mod that Ford did later that i haven't heard about.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Classic cars forum & vehicle restoration. Forum Index -> Ford All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
Forum T&C


php BB powered © php BB Grp.