Jasoncmor

Hi all.
I have a really annoying problem with my car.
Its a mk5 fiesta ZS.

Never had a problem with car up until the last few months after I did a load of work on it.

So far, everything I've done.
The thermostat housing warped one day, so I bought a new ford housing and thermostat, carried on working fine.
HCV packed up, replaced with a genuine ford one, again no problems.

Then changed cambelt, plus water pump and cylinder head temp sensor.

I removed the exhaust manifold, as I had to cut the studs off the end where the exhaust connects to the end of the cat.
I wanted to remove the cat and leave the manifold, but I snapped one of the studs bolting the manifold and cat together, so I removed the whole manifold instead, there should be 5 studs, but there are only 4 where I snapped one.

I did this work about 4 months ago.

The problem seems to be getting worse.

First of all, the car would overheat, the gauge would go to about 3/4s when driving at motorway speeds, sometimes while driving normally I would notice the fan on at full speed.

I thought there was a problem with the cooling system, I drained the coolant (which is brand new) flushed everything with a hose pipe and refilled & bled, issue still kept on happening.

I then bought a 2 part cooling system flushing product, thought it fixed the problem, but didn't.

Then I bought a brand new radiator which I then thought I had finally fixed it, but nope still happening.

The issue seems to have gotten worse.

Once the car has warmed up, weather im driving at 30 mph, or 70mph, the same thing happens, but it happens quicker when im going faster.

I can drive at 30mph for a few mins, then the temp needle will rise to about 3/4s and the fan will be on full speed, and not make a difference, I can have the heater on full blast aswell and it makes no difference at all.

I noticed my mpg went down a lot, I brimmed my tank and ive worked out previously I can travel around 50 miles before the needle moves, but I travelled 75 miles the other day, and I had 3/4s of a tank left, which isn't right. I was driving very sensibly aswell.

I think the exhaust manifold / cat is causing this issue.

I put the "secret menu" on the dash, and monitors the temps and generally while driving it will hang between 104-110*c, occasionally it will hit 114*c but no higher.

I felt the engine when I stopped, the front was warm and easily touchable, and the rear was extremely finger burning hot, and there was a load of heat rising up from the exhaust manifold / cat. The heatshields are in place.

I think my problem is the exhaust manifold / cat are heating more than it should and and making the engine overheat, is it possible the broken stud on the cat is causing a small leak, making the engine run hotter?

Also, occasionally while driving, it feels like the engine stutters very slightly, like a split second.

I noticed today that when starting from cold, there is quite a strong unburnt fuel smell, stronger than I've ever noticed before.

Does anyone have any ideas what my problem could be?

I am going to go to the ford parts desk and get some new studs / bolts and see if I can replace the broken stud and see what happens.

Does the surfaces of the cat / manifold warp when they get really hot?

If I was to get a new catalytic converter, would it be as simple as just bolting it to the manifold, or would I need a gasket or sealer of some sort?

Sorry for the long post, hopefully it makes sense.

Thanks in advanced.

Jason

Jasoncmor

Anyone have any ideas?

Churtz

I had the same issue before....felt like I was banging my head against a brick wall.....turned out to be a defective heater control valve. Was stopping the flow of coolant. New on on. Perfect instantly. Also it turns out they're super common to fail.


Matt

Jasoncmor

Well I fitted a new cat, plus new gaskets ect, problem seemed a bit better, but wasn't resolved, engine seems happier with the new cat, and there definitely isn't a ridiculous amount of heat pouring off the cat anymore.

I Bypassed the HCV, and it sorted everything.
So now, where do I stand, the HCV is basically new, bought it new from fords ages ago, only fitted a few months ago.

The serial number is 7N21 18495 AC, on the model I have.
Not sure weather this is a new one or defective one, or what, but from what I've read, the 7n21 18495 AB replaced all the older 98FU models.
But not sure on the one I have.

STeve

iTrader: (11)

chances are the valve is faulty as it happens as mentioned its really common to go wrong on fez/pumas

Jasoncmor

But on an almost new one?
It is only been installed on the car for a few months.

Stevoh200

Hi Jason did you get to the end of the problem

Stevoh200

1pd can you help me