Timing Chain Rattle..

[Sigmaproject]

Noticed that my timing chain rattle is getting to be an issue on startup..and it will rattle for a while until it builds up oil pressure (I have a TR oil pump ) Went looking for advice on the net and found this interesting item. Mainly to do with the TR pumps with the hydraulic tensioner, which were popular in performance rebuilds , but it makes for interesting reading.


Mitsubishi 2.6 TR / TS
Timing Component & Oil Pump Assy

The Mitsubishi Magna 2.6 TR & TS models were fitted with a revised design of the timing and balance shaft chain assembly, in conjunction with an updated oil pump. This revision included a hydraulic tensioner unit for the balance shaft drive chain, and a ratchet mechanism incorporated to the oil pump/tensioner plunger. This ratchet mechanism was designed to maintain tension on the timing chain at initial start up, until oil pressure was sufficient to support the plunger under normal operating conditions.

Frequently these engines are being submitted for timing assembly replacement, due to severe timing noise being present. After all the timing components have been replaced, it is not uncommon for the vehicle to be back in the workshop again after only a short time in operation (normally between 3000 to 16,000 km’s) exhibiting the same timing assembly noise symptoms.

Investigations have revealed the root cause of this condition lies primarily with the amount of wear of the hole in the oil pump, which houses the timing chain tensioner plunger. The pump is constructed with alloy, whilst the tensioner plunger shaft is manufactured from steel.

The wear in the oil pump housing appears to be caused by a number of contributing factors. When the engine is new, the tensioner plunger sits almost completely into the oil pump housing, providing a large surface supporting area. As the timing component progressively wear under normal operating conditions, the tensioner plunger extends to remove timing chain slack, as it is designed to perform. This leads to less support (shorter surface contact area) between the oil pump hole and the tensioner plunger.

Now during cold start up (remembering the ratchet unit is holding the plunger at extension) when oil pressure support is minimal, the chain vibration places high lateral load on the tensioner plunger, and due to its’ extended state, wear of the alloy oil pump hole commences. Following repeated instances of this occurrence, the oil pump hole wears to a point where the tensioner plunger has too much lateral movement for the incorporated ratchet assembly to maintain its’ grip (the ratchet teeth are fairly fine). The tensioner plunger and ratchet mating teeth may then ride across the top of each other’s surface, wearing the mating teeth. The combination of the worn ratchet mating teeth and the worn oil pump tensioner housing, render the tensioning system ineffective.

As a result, the timing chain (operating in a loose state), whips off the camshaft sprocket and bounces along the straight chain guide. The chain in due course wears through this chain guide, resulting in the severe timing noise. In addition, extensive wear may be noted on the tensioner pad, and curved chain guide.

At this time when new timing components are fitted, it is imperative to check and replace the oil pump. **

If the oil pump is not replaced, and new timing components are fitted, it is common (as mention earlier) that the engine will operate correctly for a limited period of time. This is due to the fact that all the timing components are new again, and the tensioner plunger is set almost fully back into the oil pump housing, at a zone of the hole which does not have any significant wear. As the timing components begin to settle under operating conditions and the tensioner extends, it reaches the worn section of the oil pump hole, and the same timing component failure is experienced.

Subsequent replacement of the timing components (without replacing the oil pump) will result in failure at shorter intervals, as the wear in the oil pump housing becomes more extensive.

The options to repair the oil pump/timing assembly are limited, as the problem with the oil pump must be addressed. As the OEM oil pump for this application is quite expensive, many mechanics and engine reconditioners, are opting to retrofit the engine to the earlier model (TM,TN,TP) oil pump/timing assembly setup. This is achieved by purchasing timing kit number AMBTK3, along with a new TM-TP oil pump, part number AM4G54* (the price of the aftermarket AM4G54 oil pump is significantly lower than the OEM TR,TS series oil pump).

[Sigmaproject]

This is not my engine..but is it possible to remove the timing chain cover without disturbing the head. It is that long since I had an engine in pieces I cant remember whether there are any bolts at the front of the head that may bolt thru the timing cover. Obviously the sump is not an issue

[C_Fernance]

I have taken a timing cover off before and left the head on. You still need to remove the dizzy to access the 2 bolts that go through the head into the timing cover.

[Scorpma82]

This timing chain rattle is identical to the ones in the BA V8 (the 3V versions)

Series I is pure hydraulic, series II is ratcheting

[Sigmaproject]

Thanks for the reply guys. I figure that the bottom guide must be worn thru to the metal . Actually it sounds a lot worse because I start it up in the garage, and get of the sound deflected back from the shed walls
I will have to get a balance shaft elimination kit. http://www.ebay.com.au/itm/MITSUBISHI-M ... 0335093567 which sell for $50 on eBay. I have often wondered about the quality of eBay unbranded chains and bearings..but what can you do.

[Scorpma82]

My guess would be that they are coming out of the same factory S the 'branded' version...and you are paying for the brand name (for the majority of time)

No different to buying a well known product from a food brand.....then getting the home brand...often there is no difference as they made the one company

[Sigmaproject]

Now this IS a timing chain kit.... Kit includes cam & crank gears, timing cover seal and gaskets, timing chain tensioner, timing chain guides and roller timing chains
http://www.ebay.com.au/itm/Mitsubishi-C ... 1088853773



I dont need a lot of stuff in the kit...and these kits are only listed for the older style oil pumps (up to TP) but for anyone doing a rebuild.....................

[C_Fernance]

I get a lot of my engine parts from Precision International. I wouldn't be surprised if most of the ebay sellers use them as a supplier, I know Supercheap do.

The elimination kit from them is $33.62. Postage for me is usually $12.50 no matter how much I order.

http://www.precisionintl.com/

[Sigmaproject]

They have a good search on that website. At least now I will know where to find the link
I know that this is something that I will eventually have to do. And if everything went to plan it would only take half a day. Just need to find motivation
I recently had the grill and radiator out to replace the water pump. I was halfway there.