FHC exhaust fumes in cabin

trekcarbonboy · Postby **trekcarbonboy** » 23 Oct 2011 23:13

Does anyone else with a FHC experience fumes in the cabin. Anytime I slow down the fumes come inside. Doesn't matter if I'm doing 20 or 60, just a little lift off the gas pedal and the fumes come in. This only happens with the windows down so it's not a strange hole in the cabin. I have no exhaust leaks. The exhaust tip ends about 1/2 inch shy of the bumper. I know I've seen others that project out a couple inches. Could this be the problem? I did add a small rear spoiler but had the problem before that also.

Craig '75 2.0 FHC

Beans · Postby **Beans** » 24 Oct 2011 13:25

Do you have the fresh air duct for the heater fitted?

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My Weblog[/url]</center>

trekcarbonboy · Postby **trekcarbonboy** » 24 Oct 2011 13:39

Yes.
It's exhaust fumes and I have no leaks so it shouldn't be coming from the engine bay. But I guess anythings possible.
I think I'll try extending the tailpipe a few inches.

Craig '75 2.0 FHC

HDRider · Postby **HDRider** » 24 Oct 2011 14:48

This is usually a sign of engine blow by. Having the window open causes a partial vacuume in the cabin which draws the fumes in. It is usually worse with just one window open.

Short of rebuilding the engine the only other thing to do is seal the firewall as best you can. Don't forget the seals on the cabin air intake where it meets the scuttle as they are usually missing.

Edward Hamer
Petaluma CA

FI Spyder · Postby **FI Spyder** » 24 Oct 2011 15:06

Even with fresh air duct fitted it may leak if not correctly slotted in the bottom clips. It happened to me once when I had put it back on in haste in the dark (and wrong).

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

trekcarbonboy · Postby **trekcarbonboy** » 24 Oct 2011 15:12

Ok having just looked up engine blow by this makes sense. Will make sure everything is sealed as good as possible.
Aside from an engine re-build is there anyway to reduce blow by?

Craig '75 2.0 FHC

HDRider · Postby **HDRider** » 24 Oct 2011 16:04

Make sure that the PCV system is working correctly, this will help remove some of the escaping gases before they exit the engine. Be sure to check the hose from the valve cover to ensure that it is not full of oil residue.

Edward Hamer
Petaluma CA

Hasbeen · Postby **Hasbeen** » 24 Oct 2011 16:48

Stick a bottle of STP engine oil treatment in the thing, will do wonders for reducing engine blow by.

What oil are you currently using.

Our local Triumph guru suggested Penrite HPR 40 for the 7, in good condition. This is a 25W-70, which is a little heavier than I would have thought to use, formulated for older engines, but 10 years & 60,000Km+ later using that & STP the thing doesn't use a drop of oil has good compression, & runs sweetly.

If you are using something thinner, I suggest you go to a similar weight oil, then add the STP.

Hasbeen

Beans · Postby **Beans** » 24 Oct 2011 16:57

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by trekcarbonboy

... having just looked up engine blow by this makes sense ... <hr height="1" noshade id="quote"></blockquote id="quote">
It doesn't to me as engine blow by pressurises the crankcase.
This might cause fumes to escape, depending how your crankcase breather is connected, but they are still under the bonnet
Also exhaust and crankcase fumes smell rather different .

I have never had this problem with my DHC, and I always drive with one window (partially) open.
So if you are sure it is exhaust fumes start with the obvious already mentioned,
and check the boot lid seal.

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My Weblog[/url]</center>

trekcarbonboy · Postby **trekcarbonboy** » 24 Oct 2011 18:58

THE BOOT LID SEAL! Hadn't thought of that. Definately not in proper condition. Needed a new one anyway so thats my starting point! Thanks!!!

Craig '75 2.0 FHC

RadioGuy · Postby **RadioGuy** » 24 Oct 2011 22:24

I agree with Beans, if it truly is exhaust fumes it should not be coming from the crank case. My bet is if there is not a leak, the trunk/boot lid seal would be a good place to start. The tail pipe being a little short probably doesn't help but it's probably not the main culprit.

Maintained on Saturdayâ€¦Drive on Fun-Day !!! 1976 FHC - 1980 DHC

trekcarbonboy · Postby **trekcarbonboy** » 24 Oct 2011 23:47

Just put a flashlight in the trunk and closed the lid and low and behold... Let there be light![8D] And lots of it! 3/8 inch gap all across the back. New seal will be ordered tomorrow. Thanks Beans![;)]

Craig '75 2.0 FHC

Ianftr8 · Postby **Ianftr8** » 25 Oct 2011 17:24

Whilst your replacing the seals, take a look at the rubber seal/boot on the gearlever and for that matter the hand/E brake as if these are split they can drag smells in from under the car.

Cheers
Ian

Ian Freeman
1979 TR8 DHC California car that never crossed the pond, started life as KDU 315V.
1962 Triumph Courier

trekcarbonboy · Postby **trekcarbonboy** » 12 Nov 2011 18:19

Finally took the car for a spin after replacing the trunk seal and all is well. No more fumes in the cabin.

Craig '75 2.0 FHC

Beans · Postby **Beans** » 12 Nov 2011 22:27

Good to hear you solved the problem [;)]

<center>

1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)
[url="http://www.tr7beans.blogspot.com/"]My Weblog[/url]</center>

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FHC exhaust fumes in cabin

FHC exhaust fumes in cabin

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