Knock and Rattle, but Rolls.

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Andyblahblah
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Knock and Rattle, but Rolls.

Postby Andyblahblah » Sun Jul 02, 2017 1:44 am

Hi All,
About to change the timing belt for the first time and while I'm in there, I'd like to chase down a couple other things that have been bugging me.

The first is a rattle that happens after I let off throttle -or decelerate to lower revs quickly. It sounds like a bearing rattle, and as I type, I suspect the alternator. Thought i'd see if it sounded familiar to anyone.

The other is the knock that I noticed when I filmed the first. :) The car runs fine, after a timing adjustment today, though there is a little stumble at idle. I've cleaned the idle jets, but admittedly, the carb may need a more thorough go-through. Will try to get a longer vid tomorrow.

https://youtu.be/WE9_LQzhBi0

Any immediate thoughts?
1975 Fiat Spider
1978 Fiat 128 2D Sedan
1964 GMC Handi-Van
2003 Toyota Tacoma
A bunch o motorcycles

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nelsonj
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Your car is a: 1972 Spider 124

Re: Knock and Rattle, but Rolls.

Postby nelsonj » Sun Jul 02, 2017 2:28 am

Just a guess: Sounds like the cam is hitting the valve wrong. Could be a cam lobe has worn flat, or a shim is way out of spec.
Could also be the AUX gear isn't properly aligned. Hard to tell the location from the video.
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Andyblahblah
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Your car is a: 1975 Spider

Re: Knock and Rattle, but Rolls.

Postby Andyblahblah » Sat Jul 15, 2017 1:27 am

THanks Nelson,
Was able to get another vid - it's actually coming from the exhaust it seems.
I know the PO took out all the smog stuff, but it doesn't seem like it affects much. Then again, I don't know any different.

https://youtu.be/bflOpls4Aj8
1975 Fiat Spider
1978 Fiat 128 2D Sedan
1964 GMC Handi-Van
2003 Toyota Tacoma
A bunch o motorcycles

MaineSpider75
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Your car is a: 1975 Spider 1800
Location: Scarborough, ME

Re: Knock and Rattle, but Rolls.

Postby MaineSpider75 » Mon Jul 17, 2017 6:45 pm

I have what seems to be the very same noise on my 75. It started after I replaced the timing belt last summer. I suspect the seal on my intake cam wheel is shot for a couple of reasons:
1. On occasion I get a "spray" or line of oil on the inside of my hood right near the intake cam wheel.
2. If I grab the wheel and wiggle it, there's ~5 mm of play. The exhaust wheel has no play whatsoever.

The noise and the bad seal could be unrelated, but I'm wondering if the noise I'm hearing while the engine is running could be the intake wheel rattling back and forth. Thoughts?

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blazingspider
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Re: Knock and Rattle, but Rolls.

Postby blazingspider » Tue Jul 18, 2017 7:48 am

2. If I grab the wheel and wiggle it, there's ~5 mm of play. The exhaust wheel has no play whatsoever.


If you have the "phenolic" camshaft sprockets beware. They are prone to separating between the center section and the rest of the wheel. If this condition is what is creating the play you feel you should replace the one that's failing now and the other one before it starts separating too.

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joelittel
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Re: Knock and Rattle, but Rolls.

Postby joelittel » Tue Jul 18, 2017 10:20 am

blazingspider wrote:
2. If I grab the wheel and wiggle it, there's ~5 mm of play. The exhaust wheel has no play whatsoever.


I think you need to replace that cam pulley (both actually) right away. I'm no expert but it seems to me that you might be flirting with danger.

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joelittel
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Re: Knock and Rattle, but Rolls.

Postby joelittel » Tue Jul 18, 2017 10:22 am

Or at least figure out why it has play and fix the issue.

MaineSpider75
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Re: Knock and Rattle, but Rolls.

Postby MaineSpider75 » Tue Jul 18, 2017 11:44 am

I assumed that the seal has deteriorated to the point of allowing play in the cam wheel. Is that possible?

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blazingspider
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Re: Knock and Rattle, but Rolls.

Postby blazingspider » Wed Jul 19, 2017 6:51 am

No amount of seal deterioration would result in creating play with the timing gears. Aside from the suspect phenolic timing gears separating at the centers, only wear on the journals of the camshaft or the bores of the cambox would result in creating any play.

MaineSpider75
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Your car is a: 1975 Spider 1800
Location: Scarborough, ME

Re: Knock and Rattle, but Rolls.

Postby MaineSpider75 » Wed Jul 19, 2017 8:43 am

I took a closer look at the intake wheel this morning and you are correct; the center is separating from the rest of the wheel. Since I had planned to replace the seals this weekend anyways, I ordered new intake, exhaust, and aux wheels along with the crankshaft timing gear. This will be a big job for a novice such as myself, but necessary. Will I need an impact wrench to remove the bolts? Any recommendations on how to keep the wheel from moving as I loosen the bolt (especially if the center is separating from the rest of the wheel)?

Apologies Andy if I've hijacked your thread...

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blazingspider
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Re: Knock and Rattle, but Rolls.

Postby blazingspider » Fri Jul 21, 2017 6:25 am

Using an impact wrench would probably make the job much easier. To hold a wheel in place you can use a strap wrench or an old timing belt. In your case you may want to pull the plugs and rotate the motor until the crank and cams marks line up, put the plugs back in and place the car in gear in order to help keep the cams in place.

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Andyblahblah
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Re: Knock and Rattle, but Rolls.

Postby Andyblahblah » Fri Jul 28, 2017 3:50 pm

MaineSpider75 wrote:Apologies Andy if I've hijacked your thread...


No sweat - hope yours gets sorted. :)

The rattle on mine seems pretty isolated to the exhaust. Will have a poke around today again.
1975 Fiat Spider
1978 Fiat 128 2D Sedan
1964 GMC Handi-Van
2003 Toyota Tacoma
A bunch o motorcycles

MaineSpider75
Posts: 20
Joined: Wed Jul 13, 2016 7:58 am
Your car is a: 1975 Spider 1800
Location: Scarborough, ME

Re: Knock and Rattle, but Rolls.

Postby MaineSpider75 » Sun Jul 30, 2017 1:59 pm

Update on my cam rattle:

I confirmed the intake cam wheel was indeed separating and had play in the center. Since I was already planning to replace the seals on the intake and exhaust cam wheels, I decided to order both wheels and a new timing belt. Once all of the parts arrived, I picked up a cordless impact wrench from Harbor Freight (what a godsend!). Lined everything up to TDC on #4 cylinder, and before removing the belt, I put the car in 5th gear and tackled the bolts on the intake and exhaust wheels. Both loosened without issue and the cams barely moved in the process.
Just to be safe, I snugged the bolts back on by finger and reset back to TDC before taking the belt off. Then I removed the belt and popped off the intake and exhaust wheels. Big thanks to BenjamminsFiat for his detailed explanation on replacing the timing belt and cam seals. I was able to pop out the old seals using a screwdriver (yes, you do destroy the seals getting them out). Then installed the new seals by coating them in oil and tapping them in using my 38mm socket and a hammer.
Once the seals were in place, I pulled the new cam wheels out of the box, and ran into my first problem. Neither wheel had an A or S mark on them to tell me which was the intake and which the exhaust. So I used the old wheels to help me figure it out. If you place the wheel face down with the dowel hole pointing at 12 o'clock, the timing mark on your intake wheel will be between 12 and 1 o'clock. The exhaust wheel will have the timing mark between 11 and 12 o'clock.
I then installed the new wheels and tightened with my impact wrench. Re-aligned my pointers as they had moved slightly while tightening the wheels, and then installed my new timing belt. Re-installed radiator, hoses, etc and eagerly started the engine.
The car started, but was running horribly. I was able to keep it running, but only by rotating the distributor significantly towards the #2 plug. Good news was my rattle was gone, but the timing was completely off. I thought I had been very careful to keep everything set to TDC, but I decided to try re-setting the timing belt again. I didn't want to pull the radiator out yet again, so it was a royal pain to re-set the belt, but I got it done. Timing was still horrible, and I was confident I had everything aligned to the correct marks, so I decided to quit for the night and re-think the issue.
I decided I must have done something wrong when installing the new cam wheels (perhaps I had reversed them after all?), so a few days later I tore out the radiator yet again and removed the new wheels to have a closer look at them. This time, I compared them very closely to the old wheels. I had definitely identified the correct intake and exhaust wheels, but when I looked more closely, I noticed that the timing pointer on the new exhaust wheel was in a different position relative to the dowel hole. There was probably a 10 degree difference in position between the old wheel and the new wheel. There was really nothing wrong with the old exhaust wheel, so I put it back on the car with the new intake wheel. Re-installed the belt, radiator, etc and started the engine. Voila! Back to running condition, and no rattle!!
I'm really curious as to what exhaust wheel I received vs what I ordered, but the big lesson I've learned is to really compare old parts with new in these situations before installing them.
I had also pulled the cam covers off as I needed to replace the gaskets, and I've since realized that the cam lobes on #4 cylinder should align perfectly with the timing marks on the wheels. If they don't, you've got problems :D

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blazingspider
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Re: Knock and Rattle, but Rolls.

Postby blazingspider » Mon Jul 31, 2017 5:04 am

Glad to hear you got your issue resolved.


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