View Full Version : 1986 MC - Gas Leaking from the Holly Carb?
11-28-2006, 01:01 PM
It's been a long time since my last post... NICE look to the site.... VERY NICE.
Need a little help. I am sad to say that I have not had the chance to run my boat after all of my interior work was completed last season. (Cedar Creek, TX has been too low). Have not spent the time to take it to another lake. (Most are still low in North Texas).... I have winterized my boat....thought I would put a charge on the battery and fire it up for a 15-20 second period.... It took 8-10 tries.. then it fired-up.
My Problem: Once I shut it down I was looking at the top of the engine (below the carb), and could see and smell gas. I had my wife crank it up (very briefly) so I could determine where the leak was coming from. I noticed gas coming from (right side) of a tube that runs horizontal to the engine (part of the carb) - viewing from the Port side of the boat. You can roll the tube between your fingers (like you would a fine cigar). I don't think you should be able to roll this "metal line". I have added a few pictures and welcome a reply or a call 214-668-9099 to discuss.
As always, Thanks for the help! Tom
11-28-2006, 01:31 PM
This tube is free floating between the front and rear bowls and is sealed by orings at each end. Usually it is pretty stiff. Your leak will not be continuous, it will stop when the level of the bowls recedes to that level. Winter is a good time for a carb overhaul.
11-28-2006, 01:42 PM
Thanks WilliM. Sounds like I need to contuct a "search" for Carb Overhaul.
So I might have had it flooded?
If I would have it hooked up to a "fake a lake" and let it run longer.... are you telling me that the spray of gas would end?
Not sure it should ever be spraying gas.
11-28-2006, 02:04 PM
Hi Tom...easy problem to diagnose, but maybe not so easy to fix...
Most likely you'll need to replace the small o-ring right where that tube goes into that secondary bowl. And yes, you should not be able to roll it around in your fingers like a cigar....it should be tight.
I have a 4160 (looks you have the same or similar) with the same fuel transfer tube - it moves fuel from the primary bowl at the front of the carb to the secondary bowl at the back. The whole system is pressurized so there is fuel pressure trying to get gas to the secondary bowl, and if it's not sealed properly (o-ring split or cut) the fuel will leak out from that connection point. CARBS SHOULD NEVER BE LEAKING GAS.
Here's what I did when I had a similar problem...may not be the best way, but it worked for me....
The difficult part is that you need to take off at least one of the bowls from the main carb body to get that transfer tube off. I was working on a carb rebuild at the time, so I had the entire carb off the manifold and did this on a workbench. Once you have a bowl removed, you will be able to pull that transfer tube off. Take a look at the o-ring that is sealing the tube to the secondary bowl, and I'll bet you see it's cut or smushed so as to not make a proper seal. I put back an identical new o-ring, put it all back together, and no more leak.
While the transfer tube is off, I'd take a look at the o-ring that is sealing the tube to the primary bowl as well.
Hope that helps.
11-28-2006, 02:10 PM
Thanks T. Any particular place I need to go to get an "o-ring"? Is there a difference between a "marine-o-ring" and a regular "auto-part"? MC Dealer, in-board Marine, Skidum, Pep-boys. Thanks for the FAST/Quick responses.
11-28-2006, 02:12 PM
Nope, pretty sure there's no difference in o-rings...I bought a small baggie of multiple size o-rings at the auto parts store, and put on different sizes until I was satisfied that it made a proper seal.
11-28-2006, 02:14 PM
It is fairly easy to replace the O-rings that seal each end of the transfer tube. Just remove the front bowl and the tube comes with it, or it will pull out of the front bowl and be left sticking out of the rear one. Whichever, simply pull it out, remove the o-rings and replace them and it should stop leaking. I would guess that if it started to do this spontaneously that it is a sign that the gaskets and seals are going south elsewhere in the carb as well. I Holley 'renew' kit is quite cheap and it's not too hard to do yourself.
I've attached an article that guides you through a typical rebuild. It's not a marine carb, but for these purposes, that doesn't matter.
11-28-2006, 02:17 PM
Thanks for the link. Will review now. I am sure the carb needs a complete "re-build". I assume that would be a "marine kit". Any recommendations where to purchse this from? Thanks All!
11-28-2006, 02:26 PM
You don't need a special marine kit. The marine parts are the j-tubes and the way the throttle shafts are manufactured ( I think). The rest of the carb is a normal 4160. A typical renew kit from NAPA or Autozone will have everything you need to 'refresh' your carb and make it run like new again. Interestingly enough I have seen people mess up when reinstalling the o-rings on the transfer tube. Make sure you put a little oil on them when installing or you risk damaging them when you push the tube in and you don't want to be taking it apart again to fix the problem you started out fixing this time. Also, make sure the old o-rings come out of the holes when you remove the tube!! I think the renew kists are about $35.00 in the U.S.
11-28-2006, 03:45 PM
Thanks Bruce... I will check it out... I assume (but will make sure) that the "kit" comes with new o-rings.... or will include them with my purchase. Now to find out what Model Holley Carb I have. 4010, 4150 or a 4160. Thanks again.
Last question, are the "o-rings" rubber or metal? I would think they are rubber.
11-28-2006, 04:26 PM
I'm 99.9% sure that you have a 4160 carb. The seals are just little rubber o-rings and they do come with the 'renew' kits. The kits come with all the gaskets and seals etc. you need to redo the carb. If there is something mechanical wrong (incorrect jet, worn throttle shaft etc.) then you need more parts.
I bought a Holley Techbook to help with the process when I redid mine but it wasn't that much help.
11-28-2006, 04:57 PM
Yup, thats a 4160. O-rings are rubber. For some reason the renew kit I used did not come with the O-rings for the transfer tube- so make sure they come with the kit you buy. The blue gaskets from Holley are nice because they are reusable- I would get a kit that utilizes them.
11-28-2006, 05:58 PM
Thank you, Thank you! I'll do a Google to find out where I can buy a kit for my "4160 Holley".
You guys have been GREAT!
11-28-2006, 06:09 PM
Would this work?
11-28-2006, 06:24 PM
That certainly looks like the correct kit. You should probably check the numbers to be sure but I would think it is correct. The seller has good feedback so they don't look like a scammer.
11-28-2006, 06:57 PM
I'll confirm the numbers off my Carb... then call them. They included a phone number in the auction.
11-29-2006, 01:15 PM
I got my rebuild kit from Skidim, if you look in their catalog they also recommend different bowl bolts than what you are showing in your picture. This is due to the change in gasket material I think. Anyway, after getting the kit, I had to reorder to get the bowl bolts, the original screws would not do the job any more. You have a marinized 4160, the same as on my '85.
11-29-2006, 02:18 PM
I second the motion that you get the new float bowl bolts when you rebuild the carb. The new bolts can probably be found at your local auto parts store. The primary float bowl bolts (4 of them) are a different length than the secondary float bowl bolts (4 also).
The bolts you have in the carb now will eventually be the source of a really nasty idle problem. These bolts have a "spring" built into the shank to limit the amount of clamp up on the float bowl to the carb body. With age, the original cork gaskets shrink up and with the limited clamp up from the "spring" bolts, the gaskets can shrink to a point where they block an idle circuit which makes the engine idle very badly. Been there, done that.....
By the way, I'm in Ft Worth if you need some help with the rebuild.
11-30-2006, 05:11 PM
The best price on 4160 rebuild/renew kits is at summit racing. Id call their tech line and make sure you get the right one for your list number. Also be sure to check that it contains the O-rings- try and get a kit with the new blue gaskets if you can. You may have to order the bowl bolts seperately, but Im sure Summit has those as well.
12-01-2006, 01:51 PM
Thanks guys! I'll get the numbers off the carb and order-up... will ensure that new "float bowl bolts" (4).
Bruce Carr... I would take you up on your offer, however, the boat is down on Cedar Creek. (1.5 hrs Southeast of Dallas).
Thanks for the offer.
I'll re-open the thread if I run into any issues.
Thanks again, ALL.
12-01-2006, 03:55 PM
You may or may not want to replace all of the float bowl bolts- 4 front and 4 rear.