Heater fan blowing fumes into cab

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Heater fan blowing fumes into cab

Postby xamol » Wed 11.11.2015, 10:20

Hi All, This is my first post, and my first Lotus. What a great car to drive, but I have a few niggles that I'd like to iron out!
I've had the Elan a few weeks and I've been sorting a few issues out making it into my daily driver. One of the issues I have is petrol/engine/exhaust fumes coming into the cab when stationary at lights etc. It seems worse when the blower is on, and it doesn't make a difference if it's blowing hot or cold. The fumes smell laden with petrol, like an engine running rich or on choke. So I thought it might be running too rich as the temp gauge didn't move much past the first (bottom) line. I replaced the thermostat with one from SJ SportsCars, this has fixed the low running temp as the temp gauge needle now hovers just below the second line, just about where the handbook says it should be. Unfortunately I'm still getting the fumes in the cab.
I'm worried my car is slowly poisoning me, can anyone please give me some guidance where I should be looking to find the cause of this?
Thanks
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Re: Heater fan blowing fumes into cab

Postby Enright » Thu 12.11.2015, 10:44

You could try a coolant temperature sensor - as they fail they can often account for very rich running.
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Re: Heater fan blowing fumes into cab

Postby HJ2 » Thu 12.11.2015, 11:16

Welcome aboard.

You could also check your exhaust line including manifold for cracks.
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Re: Heater fan blowing fumes into cab

Postby epipete » Thu 12.11.2015, 11:36

HJ2 wrote:Welcome aboard.

You could also check your exhaust line including manifold for cracks.


Yeah, I agree. Though logic suggests that there is a build up of fumes under the bonnet that get drawn in to the cabin when stationary. I think you need to see how much of a smell is under the bonnet in the engine bay and if you can identify a location, then how about the actual exhaust does it smell rich at the other end?

I'd also check the base timing at least that way you can confirm the engine is burning fuel efficiently, if it still smells after that then, as stated, there is a leak, Exhaust? But it's also worth checking how tight the spark plugs are, mine were, once, very loose - worth a look.
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Re: Heater fan blowing fumes into cab

Postby xamol » Thu 12.11.2015, 11:45

Cheers, I'll try all of those things.

Would I check for leaks/cracks by just eyeballing and looking for staining from exhaust fumes or is there a more scientific way to go about it?

I've checked the bulkhead/firewall for any holes that could draw fumes into the cab and I can't see any. Also I cant see any inlet for the cab ventilation, does that go through one of the wings? Basically I can't see where the fumes could get into the cab, but I'm obviously looking in the wrong places as the fumes are getting in somehow. The smell at the other end does smell a bit too, well a lot more than a modern car for example, i'm not sure if this is normal though (lack of experience shining through).
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Re: Heater fan blowing fumes into cab

Postby Enright » Thu 12.11.2015, 11:53

Oh, and there's about the most "Heath Robinson" piece of ducting you've ever seen under the LH wheelarch liner that's supposed to direct fresh air under the clamshell and into the heater. It's been mentioned recently in my seized heater controls thread (viewtopic.php?f=134&t=24837), and I suspect yours is either beyond useful life or completely missing.
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Re: Heater fan blowing fumes into cab

Postby epipete » Thu 12.11.2015, 12:45

xamol wrote:Would I check for leaks/cracks by just eyeballing and looking for staining from exhaust fumes or is there a more scientific way to go about it?


I got a great piece of kit just for this purpose - it's called a nose :-D :lol:
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Re: Heater fan blowing fumes into cab

Postby Enright » Thu 12.11.2015, 13:31

You can get a 2ft length of pipe and use it as a stethoscope to listen for any hissing noises too - it works surprisingly well.
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Re: Heater fan blowing fumes into cab

Postby Andy_J » Thu 12.11.2015, 14:17

I had a similar problem a few years ago with a smell of fumes in the cabin. In my case it turned out to be a cracked exhaust manifold. Maybe worth haveing a good look around the manifold for sooty depoists
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Re: Heater fan blowing fumes into cab

Postby HJ2 » Thu 12.11.2015, 15:33

After hitting solid ground @ Ypres (again!) this year, I'll be doing the same, as i have smelly issues as well :-(
I checked all the other connections and found some loose bolts on the exhaust manifold and a leaky gasket between Turbo and downpipe. Fixed all that, but still smell, be it a little less so at least i know I'm on the right track!

Keep us posted please :oops:
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Re: Heater fan blowing fumes into cab

Postby xamol » Fri 13.11.2015, 15:18

Excellent info there chaps, thanks very much. I'll take a look at the suspect areas this weekend and let you know what I find. 8)
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Re: Heater fan blowing fumes into cab

Postby lotusflasherman » Sat 14.11.2015, 22:29

Best way to investigate this is bing a plug up the exhaust pipe with engine ticking over and the leak should start to hiss at you. If there is no leak the engine will stall....
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Re: Heater fan blowing fumes into cab

Postby epipete » Sat 14.11.2015, 22:58

lotusflasherman wrote:Best way to investigate this is bing a plug up the exhaust pipe with engine ticking over and the leak should start to hiss at you. If there is no leak the engine will stall....


:agree: completely!
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Re: Heater fan blowing fumes into cab

Postby xamol » Mon 16.11.2015, 14:09

A quick update on the progress so far. I gave the exhaust a good once over, couldn't see round all the manifold but the bits I couldn't see I got my figers round to search for any sooty deposits, it all looks good. What doesn't look good is the exhaust joint right under the center of the car. it looks like it's blowing just a tiny bit from there. I couldn't hear it but there is a tiny pin hole with a bit of black soot around the area. I can't see how this could be feeding into the cab though.
I also had a good poke around in the passenger side wing looking for the cab ventilation intake pipe, but that came up with nothing, I couldn't see any pipe or anywhere where a pipe would run through the bulkhead so that has left me a bit flummoxed.
Next job is to fix the exhaust joint and see if that makes a difference, once I've worked out how to under the car that is! These things are so low to the ground I think that's going to be difficult without access to a lift or a pit. I normally would use a set of ramps but I've got no chance getting the Elan on my ramps.
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Re: Heater fan blowing fumes into cab

Postby Fredjohn » Mon 16.11.2015, 14:31

You need to remove the wheel arch liner on the passenger side. This may be tricky as the bolts and screws that hold it on often rust up. A stainless steel bolt/screw kit was/is available to replace all the rusted ones (both sides) if you feel like doing a bit of project creep!!

Once this is off you will see the heater inlet ducting, including the probably well deteriorated foam sleeve/joiner. You will also see the vacuum tank for the heater distribution control.
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Re: Heater fan blowing fumes into cab

Postby HJ2 » Tue 17.11.2015, 09:19

Whilst checking the spark plugs if they were seated properly (they were) I noticed a small oil leak from the valve cover. The bolts are prone to undo them selves, even when torqued to spec.
I check them every time i fiddle around in the spark plug area, but somehow they became very loose in the mean time! I can smell the hot oil when standing stationary for a traffic light.
I torqued them up at least 4 times, so the seal must be properly bedded in the recess now. I will use some locking fluid now on the bolts.

Also i ordered a new seal for the fresh cabin air intake a couple of months ago. Time to change it, clean the engine and see if the problem is solved now :D
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Re: Heater fan blowing fumes into cab

Postby Brit-Car-Nut » Tue 17.11.2015, 14:06

Fresh-Air.jpg
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Re: Heater fan blowing fumes into cab

Postby xamol » Wed 18.11.2015, 15:53

HJ2 wrote:Whilst checking the spark plugs if they were seated properly (they were) I noticed a small oil leak from the valve cover. The bolts are prone to undo them selves, even when torqued to spec.
Also i ordered a new seal for the fresh cabin air intake a couple of months ago. Time to change it, clean the engine and see if the problem is solved now :D



I also have a small oil leak from the valve cover, what is the torque spec for the bolts?

Where would the seal go? Around the hole in the above picture (thanks for that picture, a picture paints a thousand words as they say :lol: )
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Re: Heater fan blowing fumes into cab

Postby HJ2 » Wed 18.11.2015, 16:00

That's a great picture John, no more questions in terms of location, haha!
But... Mine is LHD, so pictures of that would not help in that respect much anyway.

Torque spec's are all in the manuals, dowloadable from LEC or as an alternative here:
http://www.lotusforum.be/viewtopic.php?f=11&t=265

The seal between air intake and heater system goes around the intake in John's picture as per above.
It's instant clear when you remove the wheel arch liner.
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Re: Heater fan blowing fumes into cab

Postby Brit-Car-Nut » Wed 18.11.2015, 23:17

I knew he was in the land of RHD so provided the appropriate picture.

I would be happy to provide pictures for a LHD version as well. That particular car is still in the UK but slowly getting disassembled to ship the usable bits to the US. I have several cars that have been disassembled or cut up.

The original seal is actually a foam "cuff" that goes around that connector and the one that is in the front clamshell. If you need a picture of that, the UK clam is in the storage building and I can take a picture for you.

cuff.jpg
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