Year/Model: 1966 Jetstar Eighty-Eight
Engine: 330 V8 4Br Carb.

Have had trouble with coolant leaking on top of the engine; located (or thought I located) the leak coming from the bottom of the upper hose. I replaced the upper hose, and the bypass hose while I was at it. Most of the leaking stopped with the replacement of these hoses, however, after a two hour drive I noticed some minimal leaking around the hoses onto the top of the engine. I'm almost positive that this isn't coming from the hoses. I'm not radiator/ coolant system savvy, as I've never had to work with them before, and am trying to avoid taking the Jet to a mechanic unless absolutely necessary. Can anyone give me any clue as to what else could be leaking around (practically right next to) the upper and bypass hoses?

 

The thermostat housing gasket may be the problem if pooling on the intake. I usually double the gasket there and also put some RTV there. There are only 2 bolts there. If you try this job be careful not to snap the bolts off.

 

Make sure the housing hasn't warped by putting a sheet of 120 grit sandpaper on something flat, and running the housing over it. If it's warped, it'll be obvious. You can sand it flat by this method.
Also, both bolts need sealer on the threads, as they go into the water jacket!
Make sure they're not too long, also the manifold side must be clean.
I always use lock washers, too!
2 gaskets can cause warpage!

 

I've seen them leak between the upper hose and thermostat housing if any sealer was ever used there. You may need to wire brush the entire housing to clean off residue and get a good seal.

I've also seen the housings leak at the manifold surface after a few heat-cool cycles. If you can catch it when hot, torque the bolts then. But as Maniac said, careful. Those bolts seem to be prone to snapping off after years submerged in coolant, which is why I generally install new ones anytime they're out. I also like to run a tap into the holes and clean the threads good, then use a non-hardening sealer on the threads.

One more ?- are you using a correct molded hose or a generic flex hose? www.fusick.com has molded hoses for yer Jet, and not a lot more expensive than a good Gates or NAPA hose.

Emily, where are you in NC? We may be able to put you on to a reputable mechanic familiar with old cars for things you can't or don't want to do yourself.

 

I don't have any comments on your coolant leak. It looks like the guys have covered that pretty well. But thought I'd warn you of a common problem on the 66 Jetstar 88's. The rear outer wheel bearings tend to fail and take either the axle, housing or both with them. The Jetstar rearends are next to impossible to find. And swapping to a Delta rear is a major job. I know because that's what I did on my 66 Jetstar 88. At the very least I'd check the bearings. Myself, I'd replace them if I didn't know how old they are.

Don

 

If the thermostat housing is aluminum, it is also prone to coroding right through where the hoses are in contact with the metal...so new hoses won't fill the hole in the aluminum!!

 

I believe the torque specs are around 12ft-lbs, so do not over tighten.
The threads in the manifold will thank you...

 

Thanks to everyone for your replies in such a short time; I haven't had time to do anything with the car yet, what with running around between classes all day, and it being too dark at my apartment at night to work on it However, I'm off work today and have a few hours of daylight to diagnose


@ rocketraider: Yes, I'm using the molded hoses; I went to the parts store and all they had in stock was a flex hose, and I'd never seen one before- so I ordered the correct hoses. Also, I can definitely see some blue silicon-type residue around the housing, so I'll get to cleaning that directly, as it seems the first thing I should try before replacing anything else, and I'll check for warpage on the housing as Rickman48 suggested. I'm in Greenville, where East Carolina is located, about an hour outside of Raleigh; if you know any mechanics who have experience with these old cars please let me know; the few I've been to before acted like they'd never seen a carburetor, so as of right now I'm a little uncomfortable taking it someone.

@Dapapadon: I've replaced all the bearings within the past two years; had an issue on the driver's side front hub in 2009, the whole thing was just corroded and falling apart; initially it looked like a bearing problem, but when brand new bearings would last me three days before falling to bits, I found the cause instead of the symptom in the hub. Ended up having to order a replacement hub from a salvage yard in Washington state. Haven't had any trouble with the back yet, but I'll definitely keep an eye on it, thanks for the heads up.

I'm going to take some pictures as soon as I can and upload those. Keep the tips coming, I don't have anyone else around who knows squat about any vehicle older than 1985

 

i wouldn't do the double gasket/RTV/silicone treatment. do the make sure the thermo. housing gasket/hose surfaces aren't all severly pitted. do the 120 gr. sand paper treatment thing to the flange area, maybe stuff a rag into the manifold and clean-up that mounting surface too. then get this **** called PLS(2), it's a pipe dope used by fitters, you can get a small can of it at a plumbing supply place. lightly coat both gasket surfaces, install gasket and torque the housing back down. lightly coat the hose contact area(s). slip on hoses, do not use those worm screw style hose clamps, get those factory looking ones(tower/spring clamps). if the leaks persist it's either coming from somewhere else, maybe a cracked thermo. housing or ? p. s. and lightly coated means just that, you don't need a bunch of excess crap getting run through your cooling system, this stuff also works well on alot of other gaskets, like that round one used on the air cleaner assy. to carb.

 

Okay, because I had to go to work today and couldn't find a ride, I drove the car (I did get a chance to scrape all the extra blue sealant off of the housing, but haven't had time to check the thermostat gasket; however, this may not be necessary. Read on.). After a fifteen minute drive, I checked under the hood and saw the leak; I heard a hissing (pressurized air) coming from the bottom of the upper hose, and could see tiny bubbles; upon squeezing the hose lightly, the hissing stopped and more liquid came out. SO, I think it's coming from my upper hose.

Second thing: While I was cleaning the housing I noticed a few corroded spots (pictures shown).
Is this the reason I am leaking out of a brand new hose (as Yellowstatue said)?
Can I replace the housing to fix the problem?
I've seen the packaged set of the housing, gasket, and bolts; I am probably just going to replace the whole lot. Any tips on where I may be able to find this kit for the cheapest price? Also, which brand should I go with? I've seen Spectre, TransDapt, and Mr. Gasket make the sets.

Thanks for any advice you have.

 

A wire brush on a drill works good for this.

 

I've seen worse that didn't have any issues sealing. What type hose clamp are you using? sometimes those worm clamps just don't tighten up as they should. The double wire clamp like the factory used is a great sealing clamp.

In all honesty, I'd try to find an original type housing. Those chrome plated ones like you're looking at are notorious for not sealing well either at the gasket surface or at the hose. All 65-90 Oldsmobile V8 engines used essentially the same one so shouldn't be too tough to find one. A cast iron version with the metal gooseneck for the bypass hose will work fine if you can't get the original to seal.

 

I like the Fel-Pro bluish green gaskets! They are a bit thicker and a little more expensive than the black ones sold in most auto parts stores. Use the sand paper on the housing and a tiny bit of RTV between the gasket and the housing. Install, snug bolts, let dry for about an hour, and then torque the bolts down. I use the worm style clamps, because IMO you get an even amount of pressure all the way around the hose on corroded parts.