Hello, I have a 1986 328 gts on my lift that broke one of the timing belts, looking at it from the right rear tire view it would be the left belt, my question is how to reset the cam timing on that side, right belt was ok, from reading about other models they are set at a certain degree at top dead center, can anyone supply me with the proper procedure for setting the cams back up correctly? I appreciate any input you may have.
I would think you would need to be pulling the engine out, removing the head & replacing damaged valves (maybe guides) & possibly pistons before you worry about resetting the cam timing! These are interference engines - if the belt broke while the engine was running bad things have happened. Suggest you do a leakdown test to confirm I. Edited to add: check the tensioner bearings, they are often the culprit. Also, enquiring minds (hereabouts) would be interested in knowing how old the belt was that broke - please see if you can ask the owner when it was last changed (same with the tensioner bearings)
That's a tough 1st post You do realize that the 328 has an interference engine design so the chances of having no valve damage is virtually nil right? Still, if you want to get another timing belt on it to do a compression and/or leakdown test to verify the bad news try: 0. Confirm that it's the 1-4 bank that has the broken belt (see pictures below -- the long "snout" is the end with the belts). 1. Remove 1-4 camcover (and distributor, etc.). 2. Remove 1-4 cam caps and cams -- otherwise you can't rotate the crankshaft without risking more valve damage, although if you ensure that the cams are positioned so that no valve in the 1-4 bank is fully compressed, and rotate the crankshaft gently, you may be able to skip steps 1 and 2 (although if you do steps 1 and 2, all the valves should be fully closed so you could do a compression/leakdown test in this condition without going further). 3. Rotate crankshaft CW (as viewed looking in the RH rear wheel well) until the distributor rotor inside the 5-8 distributor is pointing at the cyl #6 contact inside the 5-8 distributor cap (do this very gently since, if a valve broke, the broken piece may not allow this). 4. Rotate the crankshaft another 90 deg CW until the PM1-4 mark aligns with the flywheel pointer (this puts the crankshaft with cyl #1 at TDC and ready to fire -- when the crankshaft is in this position, all marks on the cams should line up with their corresponding reference mark on the cam cap nearest the timing belt cam drive sprocket. 5. Reinstall the 1-4 cams (and a new belt) with their mark aligned with the mark on the cam cap. (If you are new to Ferrari, don't reverse the cam caps -- note that they are stamped with a number on the cap and on the cyl head, and the numbers should be on the same side -- i.e., matching numbers one above the other.) 6. Do compression/leakdown test -- brace for bad news . Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Hello, thank you for the info, what had happened was as I was pulling the car in the parking the car stalled, after checking a few things found the distributor rotor not turning ( hence broken belt ). last question is do all four cam marks line up at top dead center cyl number1?
Yes, all four cam marks line up when cyl #1 is at TDC AND cyl #1 is at the end of its compression stroke (i.e., cyl# 1 just fired).
You will have valve damage on the bank with the broken belt. Even with the belt breaking at idle, the valves that are open will be bent. You can remove the cylinder head in the car in order to repair the damage, and are a little lucky as the rear head is easier to access than the front. Most likely the pistons are fine, as the small indentations left by the valve will not affect their operation. I would not try replacing the belt and turning the engine over any more, as you risk doing more damage to the motor. The valves that are bent will be stuck in their guides, so they will continue to interfere with the pistons if you crank the engine over.
No matter how the engine is rotated, either with the engine running, by starter, or with a wrench, if the crank is rotated with a broken timing belt there will almost assuredly be some bent valves. As per Steves excellent description above, after both cams are removed you would be able to do a leakage test to verify if it has bent valves and which cylinders. I doubt you will be lucky enough not to have bent any, but there is always the chance. The luck, if there is any, is the rear bank head can be easily removed in the car. But replace both belts because the front one is probably ready to go next. The only other item of note, the camshafts turn in opposite direction to the crankshaft. Not that it matters a great deal but when your trying to degree wheel it you have to be constantly aware which way before and after are.
Sorry to hear of your trouble. That car is a victim of the widely spread bad advice that belts don't break. Too bad. Too bad so much of it is spread here. I too have a 328 that was a victim of that same stupid philosophy. Further it was a victim of a bad repair as most are. This Thanksgiving weekend the motor is coming out to be fixed properly.
Thanks for all the responses and pictures, it is greatly appreciated, this is the first Ferrari I have had to work on and want to make sure I have the proper info before going any further. Monday will either line up the cams or remove them and do a compression test and see what happens, I just want to be sure before I sell the guy a valve job although after all the posts here that will be the case. just dont like to sell things that dont need to be done.
Honestly I cant tell you when the belt was last changed, and I dont know much about the car as far as service history other then one of the guys at the shop had worked on the car before but we dont see the car very often, I dont think it gets used much. looking at the belt there are no wear cracks from age, although there is a oil leak possibly from the cam seals, there where several teeth from the belt that where missing at the lower gear next to the crank, another concern would be that somthing had locked up causing the stripped teeth but cams are spinning free as well as tensioner pulley.
A little more profile would be nice, especially when you sound to be a member of the trade. We will all chime in to help and/or remonstrate you, but it sounds as though the car may have failed as you had it in the shop? Easy to find the workshop manual for this vehicle, most certainly it will require at minimum the removal of the rear (1-4) cylinder head. there is NOTHING to gain from resetting marks/ checking compression, believe us! It DOES have valve damage, it DOES need engine repairs. These are just nuts and bolts in the final analysis, but there are different opinions ansd standards easily found on this forum. The correct approachm IMO, is to sell the engine out, full service and repair of the head, any less is short changing the owner and is to invite future problems from the shop's perspective. Back to my hole.....
You will notice some excessive valve clearances when you remove the cam cover. Ask any of us how we know....
Pulling the cam cover and checking the cam to lifter clearance would be the least intrusive method of finding bent valves. On the 308 QV the int. is 0.20-0.25mm, the exh. is 0.35-0.40mm. I expect the 328 is the same. I'm not sure this method is foolproof, but it should detect nearly any bent valve. And I've got to believe, you've got bent ones. Now for my personal mantra: Check the cam belt drive pulley outer bearings while your at it (with the belts loose/off). They are sealed, they do not see engine oil. There should be no radial play.
Everyone should read this phrase and commit it to memory. There is not necessarily any sign in advance of failure. Age is the only reliable yardstick. I have said it here many times, most of the broken belts I have seen were perfect except for the broken part.
Quote of the decade I think. Despite a few examples of cambelts lasting 7,8 or 10 years, it's just nuts to let them go that far IMO. You only have to look at the belt change intervals VW/Audi have implemented to see that in recent years even some of the big manufacturers have realised that cam belts don't last. They had belt change intervals of 80K & even 110K miles (no specified time limit) on some of their vehicles & then suddenly a couple of years ago they shortened all belt change intervals to 4 years or 60K miles. OTOH the 2 years specified by Ferrari in Europe on 308/328s is also a bit nuts
Why don't you keep us updated on the progress and maybe even post a few pictures ? I'm sure lots of us here would like that ...
If as you say its your first Ferrari to work on consider taking more advantage of the experienced specialists here. Two of the best guys are posting to your thread as it is. Should you be replacing the belt tensioners at this point, for example. Obviously you're an experienced mechanic but we can all benefit from others' experience.
No probem with giving updates and pics of progress, will be a a little while until we talk to the customer, everyone here has been great, one of the best boards I have been on!
I was told all models, all years here in the UK. Can't say if the US is the same or not. Mind you, they have had a fair few problems with timing belts.... I got rid of an Audi earlier in the year & bought a Toyota - it has chain driven cams
